_ Git - ldk-c-bindings/blob - c-bindings-gen/src/types.rs

   1 // This file is Copyright its original authors, visible in version control
   2 // history.
   3 //
   4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE>
   5 // or the MIT license <LICENSE-MIT>, at your option.
   6 // You may not use this file except in accordance with one or both of these
   7 // licenses.
   8
   9 use std::cell::RefCell;
  10 use std::collections::{HashMap, HashSet};
  11 use std::fs::File;
  12 use std::io::Write;
  13 use std::hash;
  14
  15 use crate::blocks::*;
  16
  17 use proc_macro2::{TokenTree, Span};
  18 use quote::format_ident;
  19 use syn::parse_quote;
  20
  21 // The following utils are used purely to build our known types maps - they break down all the
  22 // types we need to resolve to include the given object, and no more.
  23
  24 pub fn first_seg_self<'a>(t: &'a syn::Type) -> Option<impl Iterator<Item=&syn::PathSegment> + 'a> {
  25         match t {
  26                 syn::Type::Path(p) => {
  27                         if p.qself.is_some() || p.path.leading_colon.is_some() {
  28                                 return None;
  29                         }
  30                         let mut segs = p.path.segments.iter();
  31                         let ty = segs.next().unwrap();
  32                         if !ty.arguments.is_empty() { return None; }
  33                         if format!("{}", ty.ident) == "Self" {
  34                                 Some(segs)
  35                         } else { None }
  36                 },
  37                 _ => None,
  38         }
  39 }
  40
  41 pub fn get_single_remaining_path_seg<'a, I: Iterator<Item=&'a syn::PathSegment>>(segs: &mut I) -> Option<&'a syn::Ident> {
  42         if let Some(ty) = segs.next() {
  43                 if !ty.arguments.is_empty() { unimplemented!(); }
  44                 if segs.next().is_some() { return None; }
  45                 Some(&ty.ident)
  46         } else { None }
  47 }
  48
  49 pub fn first_seg_is_stdlib(first_seg_str: &str) -> bool {
  50         first_seg_str == "std" || first_seg_str == "core" || first_seg_str == "alloc"
  51 }
  52
  53 pub fn single_ident_generic_path_to_ident(p: &syn::Path) -> Option<&syn::Ident> {
  54         if p.segments.len() == 1 {
  55                 Some(&p.segments.iter().next().unwrap().ident)
  56         } else { None }
  57 }
  58
  59 pub fn path_matches_nongeneric(p: &syn::Path, exp: &[&str]) -> bool {
  60         if p.segments.len() != exp.len() { return false; }
  61         for (seg, e) in p.segments.iter().zip(exp.iter()) {
  62                 if seg.arguments != syn::PathArguments::None { return false; }
  63                 if &format!("{}", seg.ident) != *e { return false; }
  64         }
  65         true
  66 }
  67
  68 pub fn string_path_to_syn_path(path: &str) -> syn::Path {
  69         let mut segments = syn::punctuated::Punctuated::new();
  70         for seg in path.split("::") {
  71                 segments.push(syn::PathSegment {
  72                         ident: syn::Ident::new(seg, Span::call_site()),
  73                         arguments: syn::PathArguments::None,
  74                 });
  75         }
  76         syn::Path { leading_colon: Some(syn::Token![::](Span::call_site())), segments }
  77 }
  78
  79 #[derive(Debug, PartialEq)]
  80 pub enum ExportStatus {
  81         Export,
  82         NoExport,
  83         TestOnly,
  84         /// This is used only for traits to indicate that users should not be able to implement their
  85         /// own version of a trait, but we should export Rust implementations of the trait (and the
  86         /// trait itself).
  87         /// Concretly, this means that we do not implement the Rust trait for the C trait struct.
  88         NotImplementable,
  89 }
  90 /// Gets the ExportStatus of an object (struct, fn, etc) given its attributes.
  91 pub fn export_status(attrs: &[syn::Attribute]) -> ExportStatus {
  92         for attr in attrs.iter() {
  93                 let tokens_clone = attr.tokens.clone();
  94                 let mut token_iter = tokens_clone.into_iter();
  95                 if let Some(token) = token_iter.next() {
  96                         match token {
  97                                 TokenTree::Punct(c) if c.as_char() == '=' => {
  98                                         // Really not sure where syn gets '=' from here -
  99                                         // it somehow represents '///' or '//!'
 100                                 },
 101                                 TokenTree::Group(g) => {
 102                                         if format!("{}", single_ident_generic_path_to_ident(&attr.path).unwrap()) == "cfg" {
 103                                                 let mut iter = g.stream().into_iter();
 104                                                 if let TokenTree::Ident(i) = iter.next().unwrap() {
 105                                                         if i == "any" {
 106                                                                 // #[cfg(any(test, feature = ""))]
 107                                                                 if let TokenTree::Group(g) = iter.next().unwrap() {
 108                                                                         let mut all_test = true;
 109                                                                         for token in g.stream().into_iter() {
 110                                                                                 if let TokenTree::Ident(i) = token {
 111                                                                                         match format!("{}", i).as_str() {
 112                                                                                                 "test" => {},
 113                                                                                                 "feature" => {},
 114                                                                                                 _ => all_test = false,
 115                                                                                         }
 116                                                                                 } else if let TokenTree::Literal(lit) = token {
 117                                                                                         if format!("{}", lit) != "fuzztarget" {
 118                                                                                                 all_test = false;
 119                                                                                         }
 120                                                                                 }
 121                                                                         }
 122                                                                         if all_test { return ExportStatus::TestOnly; }
 123                                                                 }
 124                                                         } else if i == "test" {
 125                                                                 return ExportStatus::TestOnly;
 126                                                         }
 127                                                 }
 128                                         }
 129                                         continue; // eg #[derive()]
 130                                 },
 131                                 _ => unimplemented!(),
 132                         }
 133                 } else { continue; }
 134                 match token_iter.next().unwrap() {
 135                         TokenTree::Literal(lit) => {
 136                                 let line = format!("{}", lit);
 137                                 if line.contains("(C-not exported)") {
 138                                         return ExportStatus::NoExport;
 139                                 } else if line.contains("(C-not implementable)") {
 140                                         return ExportStatus::NotImplementable;
 141                                 }
 142                         },
 143                         _ => unimplemented!(),
 144                 }
 145         }
 146         ExportStatus::Export
 147 }
 148
 149 pub fn assert_simple_bound(bound: &syn::TraitBound) {
 150         if bound.paren_token.is_some() || bound.lifetimes.is_some() { unimplemented!(); }
 151         if let syn::TraitBoundModifier::Maybe(_) = bound.modifier { unimplemented!(); }
 152 }
 153
 154 /// Returns true if the enum will be mapped as an opaue (ie struct with a pointer to the underlying
 155 /// type), otherwise it is mapped into a transparent, C-compatible version of itself.
 156 pub fn is_enum_opaque(e: &syn::ItemEnum) -> bool {
 157         for var in e.variants.iter() {
 158                 if let syn::Fields::Named(fields) = &var.fields {
 159                         for field in fields.named.iter() {
 160                                 match export_status(&field.attrs) {
 161                                         ExportStatus::Export|ExportStatus::TestOnly => {},
 162                                         ExportStatus::NotImplementable => panic!("(C-not implementable) should only appear on traits!"),
 163                                         ExportStatus::NoExport => return true,
 164                                 }
 165                         }
 166                 } else if let syn::Fields::Unnamed(fields) = &var.fields {
 167                         for field in fields.unnamed.iter() {
 168                                 match export_status(&field.attrs) {
 169                                         ExportStatus::Export|ExportStatus::TestOnly => {},
 170                                         ExportStatus::NotImplementable => panic!("(C-not implementable) should only appear on traits!"),
 171                                         ExportStatus::NoExport => return true,
 172                                 }
 173                         }
 174                 }
 175         }
 176         false
 177 }
 178
 179 /// A stack of sets of generic resolutions.
 180 ///
 181 /// This tracks the template parameters for a function, struct, or trait, allowing resolution into
 182 /// a concrete type. By pushing a new context onto the stack, this can track a function's template
 183 /// parameters inside of a generic struct or trait.
 184 ///
 185 /// It maps both direct types as well as Deref<Target = X>, mapping them via the provided
 186 /// TypeResolver's resolve_path function (ie traits map to the concrete jump table, structs to the
 187 /// concrete C container struct, etc).
 188 #[must_use]
 189 pub struct GenericTypes<'a, 'b> {
 190         self_ty: Option<String>,
 191         parent: Option<&'b GenericTypes<'b, 'b>>,
 192         typed_generics: HashMap<&'a syn::Ident, String>,
 193         default_generics: HashMap<&'a syn::Ident, (syn::Type, syn::Type)>,
 194 }
 195 impl<'a, 'p: 'a> GenericTypes<'a, 'p> {
 196         pub fn new(self_ty: Option<String>) -> Self {
 197                 Self { self_ty, parent: None, typed_generics: HashMap::new(), default_generics: HashMap::new(), }
 198         }
 199
 200         /// push a new context onto the stack, allowing for a new set of generics to be learned which
 201         /// will override any lower contexts, but which will still fall back to resoltion via lower
 202         /// contexts.
 203         pub fn push_ctx<'c>(&'c self) -> GenericTypes<'a, 'c> {
 204                 GenericTypes { self_ty: None, parent: Some(self), typed_generics: HashMap::new(), default_generics: HashMap::new(), }
 205         }
 206
 207         /// Learn the generics in generics in the current context, given a TypeResolver.
 208         pub fn learn_generics<'b, 'c>(&mut self, generics: &'a syn::Generics, types: &'b TypeResolver<'a, 'c>) -> bool {
 209                 let mut new_typed_generics = HashMap::new();
 210                 // First learn simple generics...
 211                 for generic in generics.params.iter() {
 212                         match generic {
 213                                 syn::GenericParam::Type(type_param) => {
 214                                         let mut non_lifetimes_processed = false;
 215                                         'bound_loop: for bound in type_param.bounds.iter() {
 216                                                 if let syn::TypeParamBound::Trait(trait_bound) = bound {
 217                                                         if let Some(ident) = single_ident_generic_path_to_ident(&trait_bound.path) {
 218                                                                 match &format!("{}", ident) as &str { "Send" => continue, "Sync" => continue, _ => {} }
 219                                                         }
 220                                                         if path_matches_nongeneric(&trait_bound.path, &["core", "clone", "Clone"]) { continue; }
 221
 222                                                         assert_simple_bound(&trait_bound);
 223                                                         if let Some(path) = types.maybe_resolve_path(&trait_bound.path, None) {
 224                                                                 if types.skip_path(&path) { continue; }
 225                                                                 if path == "Sized" { continue; }
 226                                                                 if non_lifetimes_processed { return false; }
 227                                                                 non_lifetimes_processed = true;
 228                                                                 if path != "std::ops::Deref" && path != "core::ops::Deref" {
 229                                                                         new_typed_generics.insert(&type_param.ident, Some(path));
 230                                                                 } else if trait_bound.path.segments.len() == 1 {
 231                                                                         // If we're templated on Deref<Target = ConcreteThing>, store
 232                                                                         // the reference type in `default_generics` which handles full
 233                                                                         // types and not just paths.
 234                                                                         if let syn::PathArguments::AngleBracketed(ref args) =
 235                                                                                         trait_bound.path.segments[0].arguments {
 236                                                                                 for subargument in args.args.iter() {
 237                                                                                         match subargument {
 238                                                                                                 syn::GenericArgument::Lifetime(_) => {},
 239                                                                                                 syn::GenericArgument::Binding(ref b) => {
 240                                                                                                         if &format!("{}", b.ident) != "Target" { return false; }
 241                                                                                                         let default = &b.ty;
 242                                                                                                         self.default_generics.insert(&type_param.ident, (parse_quote!(&#default), parse_quote!(&#default)));
 243                                                                                                         break 'bound_loop;
 244                                                                                                 },
 245                                                                                                 _ => unimplemented!(),
 246                                                                                         }
 247                                                                                 }
 248                                                                         } else {
 249                                                                                 new_typed_generics.insert(&type_param.ident, None);
 250                                                                         }
 251                                                                 }
 252                                                         }
 253                                                 }
 254                                         }
 255                                         if let Some(default) = type_param.default.as_ref() {
 256                                                 assert!(type_param.bounds.is_empty());
 257                                                 self.default_generics.insert(&type_param.ident, (default.clone(), parse_quote!(&#default)));
 258                                         }
 259                                 },
 260                                 _ => {},
 261                         }
 262                 }
 263                 // Then find generics where we are required to pass a Deref<Target=X> and pretend its just X.
 264                 if let Some(wh) = &generics.where_clause {
 265                         for pred in wh.predicates.iter() {
 266                                 if let syn::WherePredicate::Type(t) = pred {
 267                                         if let syn::Type::Path(p) = &t.bounded_ty {
 268                                                 if p.qself.is_some() { return false; }
 269                                                 if p.path.leading_colon.is_some() { return false; }
 270                                                 let mut p_iter = p.path.segments.iter();
 271                                                 if let Some(gen) = new_typed_generics.get_mut(&p_iter.next().unwrap().ident) {
 272                                                         if gen.is_some() { return false; }
 273                                                         if &format!("{}", p_iter.next().unwrap().ident) != "Target" {return false; }
 274
 275                                                         let mut non_lifetimes_processed = false;
 276                                                         for bound in t.bounds.iter() {
 277                                                                 if let syn::TypeParamBound::Trait(trait_bound) = bound {
 278                                                                         if let Some(id) = trait_bound.path.get_ident() {
 279                                                                                 if format!("{}", id) == "Sized" { continue; }
 280                                                                         }
 281                                                                         if non_lifetimes_processed { return false; }
 282                                                                         non_lifetimes_processed = true;
 283                                                                         assert_simple_bound(&trait_bound);
 284                                                                         *gen = Some(types.resolve_path(&trait_bound.path, None));
 285                                                                 }
 286                                                         }
 287                                                 } else { return false; }
 288                                         } else { return false; }
 289                                 }
 290                         }
 291                 }
 292                 for (key, value) in new_typed_generics.drain() {
 293                         if let Some(v) = value {
 294                                 assert!(self.typed_generics.insert(key, v).is_none());
 295                         } else { return false; }
 296                 }
 297                 true
 298         }
 299
 300         /// Learn the associated types from the trait in the current context.
 301         pub fn learn_associated_types<'b, 'c>(&mut self, t: &'a syn::ItemTrait, types: &'b TypeResolver<'a, 'c>) {
 302                 for item in t.items.iter() {
 303                         match item {
 304                                 &syn::TraitItem::Type(ref t) => {
 305                                         if t.default.is_some() || t.generics.lt_token.is_some() { unimplemented!(); }
 306                                         let mut bounds_iter = t.bounds.iter();
 307                                         loop {
 308                                                 match bounds_iter.next().unwrap() {
 309                                                         syn::TypeParamBound::Trait(tr) => {
 310                                                                 assert_simple_bound(&tr);
 311                                                                 if let Some(path) = types.maybe_resolve_path(&tr.path, None) {
 312                                                                         if types.skip_path(&path) { continue; }
 313                                                                         // In general we handle Deref<Target=X> as if it were just X (and
 314                                                                         // implement Deref<Target=Self> for relevant types). We don't
 315                                                                         // bother to implement it for associated types, however, so we just
 316                                                                         // ignore such bounds.
 317                                                                         if path != "std::ops::Deref" && path != "core::ops::Deref" {
 318                                                                                 self.typed_generics.insert(&t.ident, path);
 319                                                                         }
 320                                                                 } else { unimplemented!(); }
 321                                                                 for bound in bounds_iter {
 322                                                                         if let syn::TypeParamBound::Trait(_) = bound { unimplemented!(); }
 323                                                                 }
 324                                                                 break;
 325                                                         },
 326                                                         syn::TypeParamBound::Lifetime(_) => {},
 327                                                 }
 328                                         }
 329                                 },
 330                                 _ => {},
 331                         }
 332                 }
 333         }
 334
 335         /// Attempt to resolve a Path as a generic parameter and return the full path. as both a string
 336         /// and syn::Path.
 337         pub fn maybe_resolve_path<'b>(&'b self, path: &syn::Path) -> Option<&'b String> {
 338                 if let Some(ident) = path.get_ident() {
 339                         if let Some(ty) = &self.self_ty {
 340                                 if format!("{}", ident) == "Self" {
 341                                         return Some(&ty);
 342                                 }
 343                         }
 344                         if let Some(res) = self.typed_generics.get(ident) {
 345                                 return Some(res);
 346                         }
 347                 } else {
 348                         // Associated types are usually specified as "Self::Generic", so we check for that
 349                         // explicitly here.
 350                         let mut it = path.segments.iter();
 351                         if path.segments.len() == 2 && format!("{}", it.next().unwrap().ident) == "Self" {
 352                                 let ident = &it.next().unwrap().ident;
 353                                 if let Some(res) = self.typed_generics.get(ident) {
 354                                         return Some(res);
 355                                 }
 356                         }
 357                 }
 358                 if let Some(parent) = self.parent {
 359                         parent.maybe_resolve_path(path)
 360                 } else {
 361                         None
 362                 }
 363         }
 364 }
 365
 366 pub trait ResolveType<'a> { fn resolve_type(&'a self, ty: &'a syn::Type) -> &'a syn::Type; }
 367 impl<'a, 'b, 'c: 'a + 'b> ResolveType<'c> for Option<&GenericTypes<'a, 'b>> {
 368         fn resolve_type(&'c self, ty: &'c syn::Type) -> &'c syn::Type {
 369                 if let Some(us) = self {
 370                         match ty {
 371                                 syn::Type::Path(p) => {
 372                                         if let Some(ident) = p.path.get_ident() {
 373                                                 if let Some((ty, _)) = us.default_generics.get(ident) {
 374                                                         return ty;
 375                                                 }
 376                                         }
 377                                 },
 378                                 syn::Type::Reference(syn::TypeReference { elem, .. }) => {
 379                                         if let syn::Type::Path(p) = &**elem {
 380                                                 if let Some(ident) = p.path.get_ident() {
 381                                                         if let Some((_, refty)) = us.default_generics.get(ident) {
 382                                                                 return refty;
 383                                                         }
 384                                                 }
 385                                         }
 386                                 }
 387                                 _ => {},
 388                         }
 389                         us.parent.resolve_type(ty)
 390                 } else { ty }
 391         }
 392 }
 393
 394 #[derive(Clone, PartialEq)]
 395 // The type of declaration and the object itself
 396 pub enum DeclType<'a> {
 397         MirroredEnum,
 398         Trait(&'a syn::ItemTrait),
 399         StructImported { generics: &'a syn::Generics  },
 400         StructIgnored,
 401         EnumIgnored { generics: &'a syn::Generics },
 402 }
 403
 404 pub struct ImportResolver<'mod_lifetime, 'crate_lft: 'mod_lifetime> {
 405         pub crate_name: &'mod_lifetime str,
 406         dependencies: &'mod_lifetime HashSet<syn::Ident>,
 407         module_path: &'mod_lifetime str,
 408         imports: HashMap<syn::Ident, (String, syn::Path)>,
 409         declared: HashMap<syn::Ident, DeclType<'crate_lft>>,
 410         priv_modules: HashSet<syn::Ident>,
 411 }
 412 impl<'mod_lifetime, 'crate_lft: 'mod_lifetime> ImportResolver<'mod_lifetime, 'crate_lft> {
 413         fn process_use_intern(crate_name: &str, module_path: &str, dependencies: &HashSet<syn::Ident>, imports: &mut HashMap<syn::Ident, (String, syn::Path)>,
 414                         u: &syn::UseTree, partial_path: &str, mut path: syn::punctuated::Punctuated<syn::PathSegment, syn::token::Colon2>) {
 415
 416                 let new_path;
 417                 macro_rules! push_path {
 418                         ($ident: expr, $path_suffix: expr) => {
 419                                 if partial_path == "" && format!("{}", $ident) == "super" {
 420                                         let mut mod_iter = module_path.rsplitn(2, "::");
 421                                         mod_iter.next().unwrap();
 422                                         let super_mod = mod_iter.next().unwrap();
 423                                         new_path = format!("{}{}", super_mod, $path_suffix);
 424                                         assert_eq!(path.len(), 0);
 425                                         for module in super_mod.split("::") {
 426                                                 path.push(syn::PathSegment { ident: syn::Ident::new(module, Span::call_site()), arguments: syn::PathArguments::None });
 427                                         }
 428                                 } else if partial_path == "" && format!("{}", $ident) == "self" {
 429                                         new_path = format!("{}{}", module_path, $path_suffix);
 430                                         for module in module_path.split("::") {
 431                                                 path.push(syn::PathSegment { ident: syn::Ident::new(module, Span::call_site()), arguments: syn::PathArguments::None });
 432                                         }
 433                                 } else if partial_path == "" && format!("{}", $ident) == "crate" {
 434                                         new_path = format!("{}{}", crate_name, $path_suffix);
 435                                         let crate_name_ident = format_ident!("{}", crate_name);
 436                                         path.push(parse_quote!(#crate_name_ident));
 437                                 } else if partial_path == "" && !dependencies.contains(&$ident) {
 438                                         new_path = format!("{}::{}{}", crate_name, $ident, $path_suffix);
 439                                         let crate_name_ident = format_ident!("{}", crate_name);
 440                                         path.push(parse_quote!(#crate_name_ident));
 441                                 } else {
 442                                         new_path = format!("{}{}{}", partial_path, $ident, $path_suffix);
 443                                 }
 444                                 let ident = &$ident;
 445                                 path.push(parse_quote!(#ident));
 446                         }
 447                 }
 448                 match u {
 449                         syn::UseTree::Path(p) => {
 450                                 push_path!(p.ident, "::");
 451                                 Self::process_use_intern(crate_name, module_path, dependencies, imports, &p.tree, &new_path, path);
 452                         },
 453                         syn::UseTree::Name(n) => {
 454                                 push_path!(n.ident, "");
 455                                 imports.insert(n.ident.clone(), (new_path, syn::Path { leading_colon: Some(syn::Token![::](Span::call_site())), segments: path }));
 456                         },
 457                         syn::UseTree::Group(g) => {
 458                                 for i in g.items.iter() {
 459                                         Self::process_use_intern(crate_name, module_path, dependencies, imports, i, partial_path, path.clone());
 460                                 }
 461                         },
 462                         syn::UseTree::Rename(r) => {
 463                                 push_path!(r.ident, "");
 464                                 imports.insert(r.rename.clone(), (new_path, syn::Path { leading_colon: Some(syn::Token![::](Span::call_site())), segments: path }));
 465                         },
 466                         syn::UseTree::Glob(_) => {
 467                                 eprintln!("Ignoring * use for {} - this may result in resolution failures", partial_path);
 468                         },
 469                 }
 470         }
 471
 472         fn process_use(crate_name: &str, module_path: &str, dependencies: &HashSet<syn::Ident>, imports: &mut HashMap<syn::Ident, (String, syn::Path)>, u: &syn::ItemUse) {
 473                 if let syn::Visibility::Public(_) = u.vis {
 474                         // We actually only use these for #[cfg(fuzztarget)]
 475                         eprintln!("Ignoring pub(use) tree!");
 476                         return;
 477                 }
 478                 if u.leading_colon.is_some() { eprintln!("Ignoring leading-colon use!"); return; }
 479                 Self::process_use_intern(crate_name, module_path, dependencies, imports, &u.tree, "", syn::punctuated::Punctuated::new());
 480         }
 481
 482         fn insert_primitive(imports: &mut HashMap<syn::Ident, (String, syn::Path)>, id: &str) {
 483                 let ident = format_ident!("{}", id);
 484                 let path = parse_quote!(#ident);
 485                 imports.insert(ident, (id.to_owned(), path));
 486         }
 487
 488         pub fn new(crate_name: &'mod_lifetime str, dependencies: &'mod_lifetime HashSet<syn::Ident>, module_path: &'mod_lifetime str, contents: &'crate_lft [syn::Item]) -> Self {
 489                 Self::from_borrowed_items(crate_name, dependencies, module_path, &contents.iter().map(|a| a).collect::<Vec<_>>())
 490         }
 491         pub fn from_borrowed_items(crate_name: &'mod_lifetime str, dependencies: &'mod_lifetime HashSet<syn::Ident>, module_path: &'mod_lifetime str, contents: &[&'crate_lft syn::Item]) -> Self {
 492                 let mut imports = HashMap::new();
 493                 // Add primitives to the "imports" list:
 494                 Self::insert_primitive(&mut imports, "bool");
 495                 Self::insert_primitive(&mut imports, "u64");
 496                 Self::insert_primitive(&mut imports, "u32");
 497                 Self::insert_primitive(&mut imports, "u16");
 498                 Self::insert_primitive(&mut imports, "u8");
 499                 Self::insert_primitive(&mut imports, "usize");
 500                 Self::insert_primitive(&mut imports, "str");
 501                 Self::insert_primitive(&mut imports, "String");
 502
 503                 // These are here to allow us to print native Rust types in trait fn impls even if we don't
 504                 // have C mappings:
 505                 Self::insert_primitive(&mut imports, "Result");
 506                 Self::insert_primitive(&mut imports, "Vec");
 507                 Self::insert_primitive(&mut imports, "Option");
 508
 509                 let mut declared = HashMap::new();
 510                 let mut priv_modules = HashSet::new();
 511
 512                 for item in contents.iter() {
 513                         match item {
 514                                 syn::Item::Use(u) => Self::process_use(crate_name, module_path, dependencies, &mut imports, &u),
 515                                 syn::Item::Struct(s) => {
 516                                         if let syn::Visibility::Public(_) = s.vis {
 517                                                 match export_status(&s.attrs) {
 518                                                         ExportStatus::Export => { declared.insert(s.ident.clone(), DeclType::StructImported { generics: &s.generics }); },
 519                                                         ExportStatus::NoExport => { declared.insert(s.ident.clone(), DeclType::StructIgnored); },
 520                                                         ExportStatus::TestOnly => continue,
 521                                                         ExportStatus::NotImplementable => panic!("(C-not implementable) should only appear on traits!"),
 522                                                 }
 523                                         }
 524                                 },
 525                                 syn::Item::Type(t) if export_status(&t.attrs) == ExportStatus::Export => {
 526                                         if let syn::Visibility::Public(_) = t.vis {
 527                                                 declared.insert(t.ident.clone(), DeclType::StructImported { generics: &t.generics });
 528                                         }
 529                                 },
 530                                 syn::Item::Enum(e) => {
 531                                         if let syn::Visibility::Public(_) = e.vis {
 532                                                 match export_status(&e.attrs) {
 533                                                         ExportStatus::Export if is_enum_opaque(e) => { declared.insert(e.ident.clone(), DeclType::EnumIgnored { generics: &e.generics }); },
 534                                                         ExportStatus::Export => { declared.insert(e.ident.clone(), DeclType::MirroredEnum); },
 535                                                         ExportStatus::NotImplementable => panic!("(C-not implementable) should only appear on traits!"),
 536                                                         _ => continue,
 537                                                 }
 538                                         }
 539                                 },
 540                                 syn::Item::Trait(t) => {
 541                                         match export_status(&t.attrs) {
 542                                                 ExportStatus::Export|ExportStatus::NotImplementable => {
 543                                                         if let syn::Visibility::Public(_) = t.vis {
 544                                                                 declared.insert(t.ident.clone(), DeclType::Trait(t));
 545                                                         }
 546                                                 },
 547                                                 _ => continue,
 548                                         }
 549                                 },
 550                                 syn::Item::Mod(m) => {
 551                                         priv_modules.insert(m.ident.clone());
 552                                 },
 553                                 _ => {},
 554                         }
 555                 }
 556
 557                 Self { crate_name, dependencies, module_path, imports, declared, priv_modules }
 558         }
 559
 560         pub fn maybe_resolve_declared(&self, id: &syn::Ident) -> Option<&DeclType<'crate_lft>> {
 561                 self.declared.get(id)
 562         }
 563
 564         pub fn maybe_resolve_ident(&self, id: &syn::Ident) -> Option<String> {
 565                 if let Some((imp, _)) = self.imports.get(id) {
 566                         Some(imp.clone())
 567                 } else if self.declared.get(id).is_some() {
 568                         Some(self.module_path.to_string() + "::" + &format!("{}", id))
 569                 } else { None }
 570         }
 571
 572         pub fn maybe_resolve_path(&self, p: &syn::Path, generics: Option<&GenericTypes>) -> Option<String> {
 573                 if let Some(gen_types) = generics {
 574                         if let Some(resp) = gen_types.maybe_resolve_path(p) {
 575                                 return Some(resp.clone());
 576                         }
 577                 }
 578
 579                 if p.leading_colon.is_some() {
 580                         let mut res: String = p.segments.iter().enumerate().map(|(idx, seg)| {
 581                                 format!("{}{}", if idx == 0 { "" } else { "::" }, seg.ident)
 582                         }).collect();
 583                         let firstseg = p.segments.iter().next().unwrap();
 584                         if !self.dependencies.contains(&firstseg.ident) {
 585                                 res = self.crate_name.to_owned() + "::" + &res;
 586                         }
 587                         Some(res)
 588                 } else if let Some(id) = p.get_ident() {
 589                         self.maybe_resolve_ident(id)
 590                 } else {
 591                         if p.segments.len() == 1 {
 592                                 let seg = p.segments.iter().next().unwrap();
 593                                 return self.maybe_resolve_ident(&seg.ident);
 594                         }
 595                         let mut seg_iter = p.segments.iter();
 596                         let first_seg = seg_iter.next().unwrap();
 597                         let remaining: String = seg_iter.map(|seg| {
 598                                 format!("::{}", seg.ident)
 599                         }).collect();
 600                         let first_seg_str = format!("{}", first_seg.ident);
 601                         if let Some((imp, _)) = self.imports.get(&first_seg.ident) {
 602                                 if remaining != "" {
 603                                         Some(imp.clone() + &remaining)
 604                                 } else {
 605                                         Some(imp.clone())
 606                                 }
 607                         } else if let Some(_) = self.priv_modules.get(&first_seg.ident) {
 608                                 Some(format!("{}::{}{}", self.module_path, first_seg.ident, remaining))
 609                         } else if first_seg_is_stdlib(&first_seg_str) || self.dependencies.contains(&first_seg.ident) {
 610                                 Some(first_seg_str + &remaining)
 611                         } else { None }
 612                 }
 613         }
 614
 615         /// Map all the Paths in a Type into absolute paths given a set of imports (generated via process_use_intern)
 616         pub fn resolve_imported_refs(&self, mut ty: syn::Type) -> syn::Type {
 617                 match &mut ty {
 618                         syn::Type::Path(p) => {
 619                                 if p.path.segments.len() != 1 { unimplemented!(); }
 620                                 let mut args = p.path.segments[0].arguments.clone();
 621                                 if let syn::PathArguments::AngleBracketed(ref mut generics) = &mut args {
 622                                         for arg in generics.args.iter_mut() {
 623                                                 if let syn::GenericArgument::Type(ref mut t) = arg {
 624                                                         *t = self.resolve_imported_refs(t.clone());
 625                                                 }
 626                                         }
 627                                 }
 628                                 if let Some((_, newpath)) = self.imports.get(single_ident_generic_path_to_ident(&p.path).unwrap()) {
 629                                         p.path = newpath.clone();
 630                                 }
 631                                 p.path.segments[0].arguments = args;
 632                         },
 633                         syn::Type::Reference(r) => {
 634                                 r.elem = Box::new(self.resolve_imported_refs((*r.elem).clone()));
 635                         },
 636                         syn::Type::Slice(s) => {
 637                                 s.elem = Box::new(self.resolve_imported_refs((*s.elem).clone()));
 638                         },
 639                         syn::Type::Tuple(t) => {
 640                                 for e in t.elems.iter_mut() {
 641                                         *e = self.resolve_imported_refs(e.clone());
 642                                 }
 643                         },
 644                         _ => unimplemented!(),
 645                 }
 646                 ty
 647         }
 648 }
 649
 650 // templates_defined is walked to write the C++ header, so if we use the default hashing it get
 651 // reordered on each genbindings run. Instead, we use SipHasher (which defaults to 0-keys) so that
 652 // the sorting is stable across runs. It is deprecated, but the "replacement" doesn't actually
 653 // accomplish the same goals, so we just ignore it.
 654 #[allow(deprecated)]
 655 pub type NonRandomHash = hash::BuildHasherDefault<hash::SipHasher>;
 656
 657 /// A public module
 658 pub struct ASTModule {
 659         pub attrs: Vec<syn::Attribute>,
 660         pub items: Vec<syn::Item>,
 661         pub submods: Vec<String>,
 662 }
 663 /// A struct containing the syn::File AST for each file in the crate.
 664 pub struct FullLibraryAST {
 665         pub modules: HashMap<String, ASTModule, NonRandomHash>,
 666         pub dependencies: HashSet<syn::Ident>,
 667 }
 668 impl FullLibraryAST {
 669         fn load_module(&mut self, module: String, attrs: Vec<syn::Attribute>, mut items: Vec<syn::Item>) {
 670                 let mut non_mod_items = Vec::with_capacity(items.len());
 671                 let mut submods = Vec::with_capacity(items.len());
 672                 for item in items.drain(..) {
 673                         match item {
 674                                 syn::Item::Mod(m) if m.content.is_some() => {
 675                                         if export_status(&m.attrs) == ExportStatus::Export {
 676                                                 if let syn::Visibility::Public(_) = m.vis {
 677                                                         let modident = format!("{}", m.ident);
 678                                                         let modname = if module != "" {
 679                                                                 module.clone() + "::" + &modident
 680                                                         } else {
 681                                                                 modident.clone()
 682                                                         };
 683                                                         self.load_module(modname, m.attrs, m.content.unwrap().1);
 684                                                         submods.push(modident);
 685                                                 } else {
 686                                                         non_mod_items.push(syn::Item::Mod(m));
 687                                                 }
 688                                         }
 689                                 },
 690                                 syn::Item::Mod(_) => panic!("--pretty=expanded output should never have non-body modules"),
 691                                 syn::Item::ExternCrate(c) => {
 692                                         if export_status(&c.attrs) == ExportStatus::Export {
 693                                                 self.dependencies.insert(c.ident);
 694                                         }
 695                                 },
 696                                 _ => { non_mod_items.push(item); }
 697                         }
 698                 }
 699                 self.modules.insert(module, ASTModule { attrs, items: non_mod_items, submods });
 700         }
 701
 702         pub fn load_lib(lib: syn::File) -> Self {
 703                 assert_eq!(export_status(&lib.attrs), ExportStatus::Export);
 704                 let mut res = Self { modules: HashMap::default(), dependencies: HashSet::new() };
 705                 res.load_module("".to_owned(), lib.attrs, lib.items);
 706                 res
 707         }
 708 }
 709
 710 /// List of manually-generated types which are clonable
 711 fn initial_clonable_types() -> HashSet<String> {
 712         let mut res = HashSet::new();
 713         res.insert("crate::c_types::u5".to_owned());
 714         res.insert("crate::c_types::FourBytes".to_owned());
 715         res.insert("crate::c_types::TwelveBytes".to_owned());
 716         res.insert("crate::c_types::SixteenBytes".to_owned());
 717         res.insert("crate::c_types::TwentyBytes".to_owned());
 718         res.insert("crate::c_types::ThirtyTwoBytes".to_owned());
 719         res.insert("crate::c_types::SecretKey".to_owned());
 720         res.insert("crate::c_types::PublicKey".to_owned());
 721         res.insert("crate::c_types::Transaction".to_owned());
 722         res.insert("crate::c_types::TxOut".to_owned());
 723         res.insert("crate::c_types::Signature".to_owned());
 724         res.insert("crate::c_types::RecoverableSignature".to_owned());
 725         res.insert("crate::c_types::Bech32Error".to_owned());
 726         res.insert("crate::c_types::Secp256k1Error".to_owned());
 727         res.insert("crate::c_types::IOError".to_owned());
 728         res.insert("crate::c_types::Error".to_owned());
 729         res.insert("crate::c_types::Str".to_owned());
 730
 731         // Because some types are manually-mapped to CVec_u8Z we may end up checking if its clonable
 732         // before we ever get to constructing the type fully via
 733         // `write_c_mangled_container_path_intern` (which will add it here too), so we have to manually
 734         // add it on startup.
 735         res.insert("crate::c_types::derived::CVec_u8Z".to_owned());
 736         res
 737 }
 738
 739 /// Top-level struct tracking everything which has been defined while walking the crate.
 740 pub struct CrateTypes<'a> {
 741         /// This may contain structs or enums, but only when either is mapped as
 742         /// struct X { inner: *mut originalX, .. }
 743         pub opaques: HashMap<String, (&'a syn::Ident, &'a syn::Generics)>,
 744         /// structs that weren't exposed
 745         pub priv_structs: HashMap<String, &'a syn::Generics>,
 746         /// Enums which are mapped as C enums with conversion functions
 747         pub mirrored_enums: HashMap<String, &'a syn::ItemEnum>,
 748         /// Traits which are mapped as a pointer + jump table
 749         pub traits: HashMap<String, &'a syn::ItemTrait>,
 750         /// Aliases from paths to some other Type
 751         pub type_aliases: HashMap<String, syn::Type>,
 752         /// Value is an alias to Key (maybe with some generics)
 753         pub reverse_alias_map: HashMap<String, Vec<(String, syn::PathArguments)>>,
 754         /// Template continer types defined, map from mangled type name -> whether a destructor fn
 755         /// exists.
 756         ///
 757         /// This is used at the end of processing to make C++ wrapper classes
 758         pub templates_defined: RefCell<HashMap<String, bool, NonRandomHash>>,
 759         /// The output file for any created template container types, written to as we find new
 760         /// template containers which need to be defined.
 761         template_file: RefCell<&'a mut File>,
 762         /// Set of containers which are clonable
 763         clonable_types: RefCell<HashSet<String>>,
 764         /// Key impls Value
 765         pub trait_impls: HashMap<String, Vec<String>>,
 766         /// The full set of modules in the crate(s)
 767         pub lib_ast: &'a FullLibraryAST,
 768 }
 769
 770 impl<'a> CrateTypes<'a> {
 771         pub fn new(template_file: &'a mut File, libast: &'a FullLibraryAST) -> Self {
 772                 CrateTypes {
 773                         opaques: HashMap::new(), mirrored_enums: HashMap::new(), traits: HashMap::new(),
 774                         type_aliases: HashMap::new(), reverse_alias_map: HashMap::new(),
 775                         templates_defined: RefCell::new(HashMap::default()), priv_structs: HashMap::new(),
 776                         clonable_types: RefCell::new(initial_clonable_types()), trait_impls: HashMap::new(),
 777                         template_file: RefCell::new(template_file), lib_ast: &libast,
 778                 }
 779         }
 780         pub fn set_clonable(&self, object: String) {
 781                 self.clonable_types.borrow_mut().insert(object);
 782         }
 783         pub fn is_clonable(&self, object: &str) -> bool {
 784                 self.clonable_types.borrow().contains(object)
 785         }
 786         pub fn write_new_template(&self, mangled_container: String, has_destructor: bool, created_container: &[u8]) {
 787                 self.template_file.borrow_mut().write(created_container).unwrap();
 788                 self.templates_defined.borrow_mut().insert(mangled_container, has_destructor);
 789         }
 790 }
 791
 792 /// A struct which tracks resolving rust types into C-mapped equivalents, exists for one specific
 793 /// module but contains a reference to the overall CrateTypes tracking.
 794 pub struct TypeResolver<'mod_lifetime, 'crate_lft: 'mod_lifetime> {
 795         pub module_path: &'mod_lifetime str,
 796         pub crate_types: &'mod_lifetime CrateTypes<'crate_lft>,
 797         pub types: ImportResolver<'mod_lifetime, 'crate_lft>,
 798 }
 799
 800 /// Returned by write_empty_rust_val_check_suffix to indicate what type of dereferencing needs to
 801 /// happen to get the inner value of a generic.
 802 enum EmptyValExpectedTy {
 803         /// A type which has a flag for being empty (eg an array where we treat all-0s as empty).
 804         NonPointer,
 805         /// A Option mapped as a COption_*Z
 806         OptionType,
 807         /// A pointer which we want to convert to a reference.
 808         ReferenceAsPointer,
 809 }
 810
 811 #[derive(PartialEq)]
 812 /// Describes the appropriate place to print a general type-conversion string when converting a
 813 /// container.
 814 enum ContainerPrefixLocation {
 815         /// Prints a general type-conversion string prefix and suffix outside of the
 816         /// container-conversion strings.
 817         OutsideConv,
 818         /// Prints a general type-conversion string prefix and suffix inside of the
 819         /// container-conversion strings.
 820         PerConv,
 821         /// Does not print the usual type-conversion string prefix and suffix.
 822         NoPrefix,
 823 }
 824
 825 impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 826         pub fn new(module_path: &'a str, types: ImportResolver<'a, 'c>, crate_types: &'a CrateTypes<'c>) -> Self {
 827                 Self { module_path, types, crate_types }
 828         }
 829
 830         // *************************************************
 831         // *** Well know type and conversion definitions ***
 832         // *************************************************
 833
 834         /// Returns true we if can just skip passing this to C entirely
 835         pub fn skip_path(&self, full_path: &str) -> bool {
 836                 full_path == "bitcoin::secp256k1::Secp256k1" ||
 837                 full_path == "bitcoin::secp256k1::Signing" ||
 838                 full_path == "bitcoin::secp256k1::Verification"
 839         }
 840         /// Returns true we if can just skip passing this to C entirely
 841         fn no_arg_path_to_rust(&self, full_path: &str) -> &str {
 842                 if full_path == "bitcoin::secp256k1::Secp256k1" {
 843                         "secp256k1::global::SECP256K1"
 844                 } else { unimplemented!(); }
 845         }
 846
 847         /// Returns true if the object is a primitive and is mapped as-is with no conversion
 848         /// whatsoever.
 849         pub fn is_primitive(&self, full_path: &str) -> bool {
 850                 match full_path {
 851                         "bool" => true,
 852                         "u64" => true,
 853                         "u32" => true,
 854                         "u16" => true,
 855                         "u8" => true,
 856                         "usize" => true,
 857                         _ => false,
 858                 }
 859         }
 860         pub fn is_clonable(&self, ty: &str) -> bool {
 861                 if self.crate_types.is_clonable(ty) { return true; }
 862                 if self.is_primitive(ty) { return true; }
 863                 match ty {
 864                         "()" => true,
 865                         _ => false,
 866                 }
 867         }
 868         /// Gets the C-mapped type for types which are outside of the crate, or which are manually
 869         /// ignored by for some reason need mapping anyway.
 870         fn c_type_from_path<'b>(&self, full_path: &'b str, is_ref: bool, _ptr_for_ref: bool) -> Option<&'b str> {
 871                 if self.is_primitive(full_path) {
 872                         return Some(full_path);
 873                 }
 874                 match full_path {
 875                         // Note that no !is_ref types can map to an array because Rust and C's call semantics
 876                         // for arrays are different (https://github.com/eqrion/cbindgen/issues/528)
 877
 878                         "[u8; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 879                         "[u8; 20]" if !is_ref => Some("crate::c_types::TwentyBytes"),
 880                         "[u8; 16]" if !is_ref => Some("crate::c_types::SixteenBytes"),
 881                         "[u8; 12]" if !is_ref => Some("crate::c_types::TwelveBytes"),
 882                         "[u8; 4]" if !is_ref => Some("crate::c_types::FourBytes"),
 883                         "[u8; 3]" if !is_ref => Some("crate::c_types::ThreeBytes"), // Used for RGB values
 884
 885                         "str" if is_ref => Some("crate::c_types::Str"),
 886                         "alloc::string::String"|"String" => Some("crate::c_types::Str"),
 887
 888                         "std::time::Duration"|"core::time::Duration" => Some("u64"),
 889                         "std::time::SystemTime" => Some("u64"),
 890                         "std::io::Error"|"lightning::io::Error" => Some("crate::c_types::IOError"),
 891                         "core::fmt::Arguments" if is_ref => Some("crate::c_types::Str"),
 892
 893                         "core::convert::Infallible" => Some("crate::c_types::NotConstructable"),
 894
 895                         "bitcoin::bech32::Error"|"bech32::Error"
 896                                 if !is_ref => Some("crate::c_types::Bech32Error"),
 897                         "bitcoin::secp256k1::Error"|"secp256k1::Error"
 898                                 if !is_ref => Some("crate::c_types::Secp256k1Error"),
 899
 900                         "core::num::ParseIntError" => Some("crate::c_types::Error"),
 901                         "core::str::Utf8Error" => Some("crate::c_types::Error"),
 902
 903                         "bitcoin::bech32::u5"|"bech32::u5" => Some("crate::c_types::u5"),
 904                         "core::num::NonZeroU8" => Some("u8"),
 905
 906                         "secp256k1::PublicKey"|"bitcoin::secp256k1::PublicKey" => Some("crate::c_types::PublicKey"),
 907                         "bitcoin::secp256k1::ecdsa::Signature" => Some("crate::c_types::Signature"),
 908                         "bitcoin::secp256k1::ecdsa::RecoverableSignature" => Some("crate::c_types::RecoverableSignature"),
 909                         "bitcoin::secp256k1::SecretKey" if is_ref  => Some("*const [u8; 32]"),
 910                         "bitcoin::secp256k1::SecretKey" if !is_ref => Some("crate::c_types::SecretKey"),
 911                         "bitcoin::blockdata::script::Script" if is_ref => Some("crate::c_types::u8slice"),
 912                         "bitcoin::blockdata::script::Script" if !is_ref => Some("crate::c_types::derived::CVec_u8Z"),
 913                         "bitcoin::blockdata::transaction::OutPoint" => Some("crate::lightning::chain::transaction::OutPoint"),
 914                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" => Some("crate::c_types::Transaction"),
 915                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some("crate::c_types::TxOut"),
 916                         "bitcoin::network::constants::Network" => Some("crate::bitcoin::network::Network"),
 917                         "bitcoin::util::address::WitnessVersion" => Some("crate::c_types::WitnessVersion"),
 918                         "bitcoin::blockdata::block::BlockHeader" if is_ref  => Some("*const [u8; 80]"),
 919                         "bitcoin::blockdata::block::Block" if is_ref  => Some("crate::c_types::u8slice"),
 920
 921                         "bitcoin::hash_types::PubkeyHash"|"bitcoin::hash_types::WPubkeyHash"|"bitcoin::hash_types::ScriptHash"
 922                                 if is_ref => Some("*const [u8; 20]"),
 923                         "bitcoin::hash_types::WScriptHash"
 924                                 if is_ref => Some("*const [u8; 32]"),
 925
 926                         // Newtypes that we just expose in their original form.
 927                         "bitcoin::hash_types::Txid"|"bitcoin::hash_types::BlockHash"|"bitcoin_hashes::sha256::Hash"
 928                                 if is_ref  => Some("*const [u8; 32]"),
 929                         "bitcoin::hash_types::Txid"|"bitcoin::hash_types::BlockHash"|"bitcoin_hashes::sha256::Hash"
 930                                 if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 931                         "bitcoin::secp256k1::Message" if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 932                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
 933                         |"lightning::ln::channelmanager::PaymentId"|"lightning::chain::keysinterface::KeyMaterial"
 934                                 if is_ref => Some("*const [u8; 32]"),
 935                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
 936                         |"lightning::ln::channelmanager::PaymentId"|"lightning::chain::keysinterface::KeyMaterial"
 937                                 if !is_ref => Some("crate::c_types::ThirtyTwoBytes"),
 938
 939                         "lightning::io::Read" => Some("crate::c_types::u8slice"),
 940
 941                         _ => None,
 942                 }
 943         }
 944
 945         fn from_c_conversion_new_var_from_path<'b>(&self, _full_path: &str, _is_ref: bool) -> Option<(&'b str, &'b str)> {
 946                 None
 947         }
 948         fn from_c_conversion_prefix_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<String> {
 949                 if self.is_primitive(full_path) {
 950                         return Some("".to_owned());
 951                 }
 952                 match full_path {
 953                         "Vec" if !is_ref => Some("local_"),
 954                         "Result" if !is_ref => Some("local_"),
 955                         "Option" if is_ref => Some("&local_"),
 956                         "Option" => Some("local_"),
 957
 958                         "[u8; 32]" if is_ref => Some("unsafe { &*"),
 959                         "[u8; 32]" if !is_ref => Some(""),
 960                         "[u8; 20]" if !is_ref => Some(""),
 961                         "[u8; 16]" if !is_ref => Some(""),
 962                         "[u8; 12]" if !is_ref => Some(""),
 963                         "[u8; 4]" if !is_ref => Some(""),
 964                         "[u8; 3]" if !is_ref => Some(""),
 965
 966                         "[u8]" if is_ref => Some(""),
 967                         "[usize]" if is_ref => Some(""),
 968
 969                         "str" if is_ref => Some(""),
 970                         "alloc::string::String"|"String" => Some(""),
 971                         "std::io::Error"|"lightning::io::Error" => Some(""),
 972                         // Note that we'll panic for String if is_ref, as we only have non-owned memory, we
 973                         // cannot create a &String.
 974
 975                         "core::convert::Infallible" => Some("panic!(\"You must never construct a NotConstructable! : "),
 976
 977                         "bitcoin::bech32::Error"|"bech32::Error" if !is_ref => Some(""),
 978                         "bitcoin::secp256k1::Error"|"secp256k1::Error" if !is_ref => Some(""),
 979
 980                         "core::num::ParseIntError" => Some("u8::from_str_radix(\" a\", 10).unwrap_err() /*"),
 981                         "core::str::Utf8Error" => Some("core::str::from_utf8(&[0xff]).unwrap_err() /*"),
 982
 983                         "std::time::Duration"|"core::time::Duration" => Some("core::time::Duration::from_secs("),
 984                         "std::time::SystemTime" => Some("(::std::time::SystemTime::UNIX_EPOCH + std::time::Duration::from_secs("),
 985
 986                         "bitcoin::bech32::u5"|"bech32::u5" => Some(""),
 987                         "core::num::NonZeroU8" => Some("core::num::NonZeroU8::new("),
 988
 989                         "bitcoin::secp256k1::PublicKey"|"secp256k1::PublicKey" if is_ref => Some("&"),
 990                         "bitcoin::secp256k1::PublicKey"|"secp256k1::PublicKey" => Some(""),
 991                         "bitcoin::secp256k1::ecdsa::Signature" if is_ref => Some("&"),
 992                         "bitcoin::secp256k1::ecdsa::Signature" => Some(""),
 993                         "bitcoin::secp256k1::ecdsa::RecoverableSignature" => Some(""),
 994                         "bitcoin::secp256k1::SecretKey" if is_ref => Some("&::bitcoin::secp256k1::SecretKey::from_slice(&unsafe { *"),
 995                         "bitcoin::secp256k1::SecretKey" if !is_ref => Some(""),
 996                         "bitcoin::blockdata::script::Script" if is_ref => Some("&::bitcoin::blockdata::script::Script::from(Vec::from("),
 997                         "bitcoin::blockdata::script::Script" if !is_ref => Some("::bitcoin::blockdata::script::Script::from("),
 998                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" if is_ref => Some("&"),
 999                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" => Some(""),
1000                         "bitcoin::blockdata::transaction::OutPoint" => Some("crate::c_types::C_to_bitcoin_outpoint("),
1001                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(""),
1002                         "bitcoin::network::constants::Network" => Some(""),
1003                         "bitcoin::util::address::WitnessVersion" => Some(""),
1004                         "bitcoin::blockdata::block::BlockHeader" => Some("&::bitcoin::consensus::encode::deserialize(unsafe { &*"),
1005                         "bitcoin::blockdata::block::Block" if is_ref => Some("&::bitcoin::consensus::encode::deserialize("),
1006
1007                         "bitcoin::hash_types::PubkeyHash" if is_ref =>
1008                                 Some("&bitcoin::hash_types::PubkeyHash::from_hash(bitcoin::hashes::Hash::from_inner(unsafe { *"),
1009                         "bitcoin::hash_types::WPubkeyHash" if is_ref =>
1010                                 Some("&bitcoin::hash_types::WPubkeyHash::from_hash(bitcoin::hashes::Hash::from_inner(unsafe { *"),
1011                         "bitcoin::hash_types::ScriptHash" if is_ref =>
1012                                 Some("&bitcoin::hash_types::ScriptHash::from_hash(bitcoin::hashes::Hash::from_inner(unsafe { *"),
1013                         "bitcoin::hash_types::WScriptHash" if is_ref =>
1014                                 Some("&bitcoin::hash_types::WScriptHash::from_hash(bitcoin::hashes::Hash::from_inner(unsafe { *"),
1015
1016                         // Newtypes that we just expose in their original form.
1017                         "bitcoin::hash_types::Txid" if is_ref => Some("&::bitcoin::hash_types::Txid::from_slice(&unsafe { &*"),
1018                         "bitcoin::hash_types::Txid" if !is_ref => Some("::bitcoin::hash_types::Txid::from_slice(&"),
1019                         "bitcoin::hash_types::BlockHash" => Some("::bitcoin::hash_types::BlockHash::from_slice(&"),
1020                         "lightning::ln::PaymentHash" if !is_ref => Some("::lightning::ln::PaymentHash("),
1021                         "lightning::ln::PaymentHash" if is_ref => Some("&::lightning::ln::PaymentHash(unsafe { *"),
1022                         "lightning::ln::PaymentPreimage" if !is_ref => Some("::lightning::ln::PaymentPreimage("),
1023                         "lightning::ln::PaymentPreimage" if is_ref => Some("&::lightning::ln::PaymentPreimage(unsafe { *"),
1024                         "lightning::ln::PaymentSecret" if !is_ref => Some("::lightning::ln::PaymentSecret("),
1025                         "lightning::ln::channelmanager::PaymentId" if !is_ref => Some("::lightning::ln::channelmanager::PaymentId("),
1026                         "lightning::ln::channelmanager::PaymentId" if is_ref=> Some("&::lightning::ln::channelmanager::PaymentId( unsafe { *"),
1027                         "lightning::chain::keysinterface::KeyMaterial" if !is_ref => Some("::lightning::chain::keysinterface::KeyMaterial("),
1028                         "lightning::chain::keysinterface::KeyMaterial" if is_ref=> Some("&::lightning::chain::keysinterface::KeyMaterial( unsafe { *"),
1029
1030                         // List of traits we map (possibly during processing of other files):
1031                         "lightning::io::Read" => Some("&mut "),
1032
1033                         _ => None,
1034                 }.map(|s| s.to_owned())
1035         }
1036         fn from_c_conversion_suffix_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<String> {
1037                 if self.is_primitive(full_path) {
1038                         return Some("".to_owned());
1039                 }
1040                 match full_path {
1041                         "Vec" if !is_ref => Some(""),
1042                         "Option" => Some(""),
1043                         "Result" if !is_ref => Some(""),
1044
1045                         "[u8; 32]" if is_ref => Some("}"),
1046                         "[u8; 32]" if !is_ref => Some(".data"),
1047                         "[u8; 20]" if !is_ref => Some(".data"),
1048                         "[u8; 16]" if !is_ref => Some(".data"),
1049                         "[u8; 12]" if !is_ref => Some(".data"),
1050                         "[u8; 4]" if !is_ref => Some(".data"),
1051                         "[u8; 3]" if !is_ref => Some(".data"),
1052
1053                         "[u8]" if is_ref => Some(".to_slice()"),
1054                         "[usize]" if is_ref => Some(".to_slice()"),
1055
1056                         "str" if is_ref => Some(".into_str()"),
1057                         "alloc::string::String"|"String" => Some(".into_string()"),
1058                         "std::io::Error"|"lightning::io::Error" => Some(".to_rust()"),
1059
1060                         "core::convert::Infallible" => Some("\")"),
1061
1062                         "bitcoin::bech32::Error"|"bech32::Error" if !is_ref => Some(".into_rust()"),
1063                         "bitcoin::secp256k1::Error"|"secp256k1::Error" if !is_ref => Some(".into_rust()"),
1064
1065                         "core::num::ParseIntError" => Some("*/"),
1066                         "core::str::Utf8Error" => Some("*/"),
1067
1068                         "std::time::Duration"|"core::time::Duration" => Some(")"),
1069                         "std::time::SystemTime" => Some("))"),
1070
1071                         "bitcoin::bech32::u5"|"bech32::u5" => Some(".into()"),
1072                         "core::num::NonZeroU8" => Some(").expect(\"Value must be non-zero\")"),
1073
1074                         "bitcoin::secp256k1::PublicKey"|"secp256k1::PublicKey" => Some(".into_rust()"),
1075                         "bitcoin::secp256k1::ecdsa::Signature" => Some(".into_rust()"),
1076                         "bitcoin::secp256k1::ecdsa::RecoverableSignature" => Some(".into_rust()"),
1077                         "bitcoin::secp256k1::SecretKey" if !is_ref => Some(".into_rust()"),
1078                         "bitcoin::secp256k1::SecretKey" if is_ref => Some("}[..]).unwrap()"),
1079                         "bitcoin::blockdata::script::Script" if is_ref => Some(".to_slice()))"),
1080                         "bitcoin::blockdata::script::Script" if !is_ref => Some(".into_rust())"),
1081                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" => Some(".into_bitcoin()"),
1082                         "bitcoin::blockdata::transaction::OutPoint" => Some(")"),
1083                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(".into_rust()"),
1084                         "bitcoin::network::constants::Network" => Some(".into_bitcoin()"),
1085                         "bitcoin::util::address::WitnessVersion" => Some(".into()"),
1086                         "bitcoin::blockdata::block::BlockHeader" => Some(" }).unwrap()"),
1087                         "bitcoin::blockdata::block::Block" => Some(".to_slice()).unwrap()"),
1088
1089                         "bitcoin::hash_types::PubkeyHash"|"bitcoin::hash_types::WPubkeyHash"|
1090                         "bitcoin::hash_types::ScriptHash"|"bitcoin::hash_types::WScriptHash"
1091                                 if is_ref => Some(" }.clone()))"),
1092
1093                         // Newtypes that we just expose in their original form.
1094                         "bitcoin::hash_types::Txid" if is_ref => Some(" }[..]).unwrap()"),
1095                         "bitcoin::hash_types::Txid" => Some(".data[..]).unwrap()"),
1096                         "bitcoin::hash_types::BlockHash" if !is_ref => Some(".data[..]).unwrap()"),
1097                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1098                         |"lightning::ln::channelmanager::PaymentId"|"lightning::chain::keysinterface::KeyMaterial"
1099                                 if !is_ref => Some(".data)"),
1100                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1101                         |"lightning::ln::channelmanager::PaymentId"|"lightning::chain::keysinterface::KeyMaterial"
1102                                 if is_ref => Some(" })"),
1103
1104                         // List of traits we map (possibly during processing of other files):
1105                         "lightning::io::Read" => Some(".to_reader()"),
1106
1107                         _ => None,
1108                 }.map(|s| s.to_owned())
1109         }
1110
1111         fn to_c_conversion_new_var_from_path<'b>(&self, full_path: &str, is_ref: bool) -> Option<(&'b str, &'b str)> {
1112                 if self.is_primitive(full_path) {
1113                         return None;
1114                 }
1115                 match full_path {
1116                         "[u8]" if is_ref => Some(("crate::c_types::u8slice::from_slice(", ")")),
1117                         "[usize]" if is_ref => Some(("crate::c_types::usizeslice::from_slice(", ")")),
1118
1119                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some(("{ let mut s = [0u8; 80]; s[..].copy_from_slice(&::bitcoin::consensus::encode::serialize(", ")); s }")),
1120                         "bitcoin::blockdata::block::Block" if is_ref => Some(("::bitcoin::consensus::encode::serialize(", ")")),
1121                         "bitcoin::hash_types::Txid" => None,
1122
1123                         _ => None,
1124                 }.map(|s| s.to_owned())
1125         }
1126         fn to_c_conversion_inline_prefix_from_path(&self, full_path: &str, is_ref: bool, _ptr_for_ref: bool) -> Option<String> {
1127                 if self.is_primitive(full_path) {
1128                         return Some("".to_owned());
1129                 }
1130                 match full_path {
1131                         "Result" if !is_ref => Some("local_"),
1132                         "Vec" if !is_ref => Some("local_"),
1133                         "Option" => Some("local_"),
1134
1135                         "[u8; 32]" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
1136                         "[u8; 32]" if is_ref => Some(""),
1137                         "[u8; 20]" if !is_ref => Some("crate::c_types::TwentyBytes { data: "),
1138                         "[u8; 16]" if !is_ref => Some("crate::c_types::SixteenBytes { data: "),
1139                         "[u8; 12]" if !is_ref => Some("crate::c_types::TwelveBytes { data: "),
1140                         "[u8; 4]" if !is_ref => Some("crate::c_types::FourBytes { data: "),
1141                         "[u8; 3]" if is_ref => Some(""),
1142
1143                         "[u8]" if is_ref => Some("local_"),
1144                         "[usize]" if is_ref => Some("local_"),
1145
1146                         "str" if is_ref => Some(""),
1147                         "alloc::string::String"|"String" => Some(""),
1148
1149                         "std::time::Duration"|"core::time::Duration" => Some(""),
1150                         "std::time::SystemTime" => Some(""),
1151                         "std::io::Error"|"lightning::io::Error" => Some("crate::c_types::IOError::from_rust("),
1152                         "core::fmt::Arguments" => Some("alloc::format!(\"{}\", "),
1153
1154                         "core::convert::Infallible" => Some("panic!(\"Cannot construct an Infallible: "),
1155
1156                         "bitcoin::bech32::Error"|"bech32::Error"
1157                                 if !is_ref => Some("crate::c_types::Bech32Error::from_rust("),
1158                         "bitcoin::secp256k1::Error"|"secp256k1::Error"
1159                                 if !is_ref => Some("crate::c_types::Secp256k1Error::from_rust("),
1160
1161                         "core::num::ParseIntError" => Some("crate::c_types::Error { _dummy: 0 } /*"),
1162                         "core::str::Utf8Error" => Some("crate::c_types::Error { _dummy: 0 } /*"),
1163
1164                         "bitcoin::bech32::u5"|"bech32::u5" => Some(""),
1165
1166                         "bitcoin::secp256k1::PublicKey"|"secp256k1::PublicKey" => Some("crate::c_types::PublicKey::from_rust(&"),
1167                         "bitcoin::secp256k1::ecdsa::Signature" => Some("crate::c_types::Signature::from_rust(&"),
1168                         "bitcoin::secp256k1::ecdsa::RecoverableSignature" => Some("crate::c_types::RecoverableSignature::from_rust(&"),
1169                         "bitcoin::secp256k1::SecretKey" if is_ref => Some(""),
1170                         "bitcoin::secp256k1::SecretKey" if !is_ref => Some("crate::c_types::SecretKey::from_rust("),
1171                         "bitcoin::blockdata::script::Script" if is_ref => Some("crate::c_types::u8slice::from_slice(&"),
1172                         "bitcoin::blockdata::script::Script" if !is_ref => Some(""),
1173                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" if is_ref => Some("crate::c_types::Transaction::from_bitcoin("),
1174                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" => Some("crate::c_types::Transaction::from_bitcoin(&"),
1175                         "bitcoin::blockdata::transaction::OutPoint" => Some("crate::c_types::bitcoin_to_C_outpoint("),
1176                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some("crate::c_types::TxOut::from_rust("),
1177                         "bitcoin::network::constants::Network" => Some("crate::bitcoin::network::Network::from_bitcoin("),
1178                         "bitcoin::util::address::WitnessVersion" => Some(""),
1179                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some("&local_"),
1180                         "bitcoin::blockdata::block::Block" if is_ref => Some("crate::c_types::u8slice::from_slice(&local_"),
1181
1182                         "bitcoin::hash_types::Txid" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
1183
1184                         // Newtypes that we just expose in their original form.
1185                         "bitcoin::hash_types::Txid"|"bitcoin::hash_types::BlockHash"|"bitcoin_hashes::sha256::Hash"
1186                                 if is_ref => Some(""),
1187                         "bitcoin::hash_types::Txid"|"bitcoin::hash_types::BlockHash"|"bitcoin_hashes::sha256::Hash"
1188                                 if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
1189                         "bitcoin::secp256k1::Message" if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
1190                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1191                         |"lightning::ln::channelmanager::PaymentId"|"lightning::chain::keysinterface::KeyMaterial"
1192                                 if is_ref => Some("&"),
1193                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1194                         |"lightning::ln::channelmanager::PaymentId"|"lightning::chain::keysinterface::KeyMaterial"
1195                                 if !is_ref => Some("crate::c_types::ThirtyTwoBytes { data: "),
1196
1197                         "lightning::io::Read" => Some("crate::c_types::u8slice::from_vec(&crate::c_types::reader_to_vec("),
1198
1199                         _ => None,
1200                 }.map(|s| s.to_owned())
1201         }
1202         fn to_c_conversion_inline_suffix_from_path(&self, full_path: &str, is_ref: bool, _ptr_for_ref: bool) -> Option<String> {
1203                 if self.is_primitive(full_path) {
1204                         return Some("".to_owned());
1205                 }
1206                 match full_path {
1207                         "Result" if !is_ref => Some(""),
1208                         "Vec" if !is_ref => Some(".into()"),
1209                         "Option" => Some(""),
1210
1211                         "[u8; 32]" if !is_ref => Some(" }"),
1212                         "[u8; 32]" if is_ref => Some(""),
1213                         "[u8; 20]" if !is_ref => Some(" }"),
1214                         "[u8; 16]" if !is_ref => Some(" }"),
1215                         "[u8; 12]" if !is_ref => Some(" }"),
1216                         "[u8; 4]" if !is_ref => Some(" }"),
1217                         "[u8; 3]" if is_ref => Some(""),
1218
1219                         "[u8]" if is_ref => Some(""),
1220                         "[usize]" if is_ref => Some(""),
1221
1222                         "str" if is_ref => Some(".into()"),
1223                         "alloc::string::String"|"String" if is_ref => Some(".as_str().into()"),
1224                         "alloc::string::String"|"String" => Some(".into()"),
1225
1226                         "std::time::Duration"|"core::time::Duration" => Some(".as_secs()"),
1227                         "std::time::SystemTime" => Some(".duration_since(::std::time::SystemTime::UNIX_EPOCH).expect(\"Times must be post-1970\").as_secs()"),
1228                         "std::io::Error"|"lightning::io::Error" => Some(")"),
1229                         "core::fmt::Arguments" => Some(").into()"),
1230
1231                         "core::convert::Infallible" => Some("\")"),
1232
1233                         "bitcoin::secp256k1::Error"|"bech32::Error"
1234                                 if !is_ref => Some(")"),
1235                         "bitcoin::secp256k1::Error"|"secp256k1::Error"
1236                                 if !is_ref => Some(")"),
1237
1238                         "core::num::ParseIntError" => Some("*/"),
1239                         "core::str::Utf8Error" => Some("*/"),
1240
1241                         "bitcoin::bech32::u5"|"bech32::u5" => Some(".into()"),
1242
1243                         "bitcoin::secp256k1::PublicKey"|"secp256k1::PublicKey" => Some(")"),
1244                         "bitcoin::secp256k1::ecdsa::Signature" => Some(")"),
1245                         "bitcoin::secp256k1::ecdsa::RecoverableSignature" => Some(")"),
1246                         "bitcoin::secp256k1::SecretKey" if !is_ref => Some(")"),
1247                         "bitcoin::secp256k1::SecretKey" if is_ref => Some(".as_ref()"),
1248                         "bitcoin::blockdata::script::Script" if is_ref => Some("[..])"),
1249                         "bitcoin::blockdata::script::Script" if !is_ref => Some(".into_bytes().into()"),
1250                         "bitcoin::blockdata::transaction::Transaction"|"bitcoin::Transaction" => Some(")"),
1251                         "bitcoin::blockdata::transaction::OutPoint" => Some(")"),
1252                         "bitcoin::blockdata::transaction::TxOut" if !is_ref => Some(")"),
1253                         "bitcoin::network::constants::Network" => Some(")"),
1254                         "bitcoin::util::address::WitnessVersion" => Some(".into()"),
1255                         "bitcoin::blockdata::block::BlockHeader" if is_ref => Some(""),
1256                         "bitcoin::blockdata::block::Block" if is_ref => Some(")"),
1257
1258                         "bitcoin::hash_types::Txid" if !is_ref => Some(".into_inner() }"),
1259
1260                         // Newtypes that we just expose in their original form.
1261                         "bitcoin::hash_types::Txid"|"bitcoin::hash_types::BlockHash"|"bitcoin_hashes::sha256::Hash"
1262                                 if is_ref => Some(".as_inner()"),
1263                         "bitcoin::hash_types::Txid"|"bitcoin::hash_types::BlockHash"|"bitcoin_hashes::sha256::Hash"
1264                                 if !is_ref => Some(".into_inner() }"),
1265                         "bitcoin::secp256k1::Message" if !is_ref => Some(".as_ref().clone() }"),
1266                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1267                         |"lightning::ln::channelmanager::PaymentId"|"lightning::chain::keysinterface::KeyMaterial"
1268                                 if is_ref => Some(".0"),
1269                         "lightning::ln::PaymentHash"|"lightning::ln::PaymentPreimage"|"lightning::ln::PaymentSecret"
1270                         |"lightning::ln::channelmanager::PaymentId"|"lightning::chain::keysinterface::KeyMaterial"
1271                                 if !is_ref => Some(".0 }"),
1272
1273                         "lightning::io::Read" => Some("))"),
1274
1275                         _ => None,
1276                 }.map(|s| s.to_owned())
1277         }
1278
1279         fn empty_val_check_suffix_from_path(&self, full_path: &str) -> Option<&str> {
1280                 match full_path {
1281                         "lightning::ln::PaymentSecret" => Some(".data == [0; 32]"),
1282                         "secp256k1::PublicKey"|"bitcoin::secp256k1::PublicKey" => Some(".is_null()"),
1283                         "bitcoin::secp256k1::ecdsa::Signature" => Some(".is_null()"),
1284                         _ => None
1285                 }
1286         }
1287
1288         /// When printing a reference to the source crate's rust type, if we need to map it to a
1289         /// different "real" type, it can be done so here.
1290         /// This is useful to work around limitations in the binding type resolver, where we reference
1291         /// a non-public `use` alias.
1292         /// TODO: We should never need to use this!
1293         fn real_rust_type_mapping<'equiv>(&self, thing: &'equiv str) -> &'equiv str {
1294                 match thing {
1295                         "lightning::io::Read" => "crate::c_types::io::Read",
1296                         _ => thing,
1297                 }
1298         }
1299
1300         // ****************************
1301         // *** Container Processing ***
1302         // ****************************
1303
1304         /// Returns the module path in the generated mapping crate to the containers which we generate
1305         /// when writing to CrateTypes::template_file.
1306         pub fn generated_container_path() -> &'static str {
1307                 "crate::c_types::derived"
1308         }
1309         /// Returns the module path in the generated mapping crate to the container templates, which
1310         /// are then concretized and put in the generated container path/template_file.
1311         fn container_templ_path() -> &'static str {
1312                 "crate::c_types"
1313         }
1314
1315         /// Returns true if the path containing the given args is a "transparent" container, ie an
1316         /// Option or a container which does not require a generated continer class.
1317         fn is_transparent_container<'i, I: Iterator<Item=&'i syn::Type>>(&self, full_path: &str, _is_ref: bool, mut args: I, generics: Option<&GenericTypes>) -> bool {
1318                 if full_path == "Option" {
1319                         let inner = args.next().unwrap();
1320                         assert!(args.next().is_none());
1321                         match inner {
1322                                 syn::Type::Reference(_) => true,
1323                                 syn::Type::Array(a) => {
1324                                         if let syn::Expr::Lit(l) = &a.len {
1325                                                 if let syn::Lit::Int(i) = &l.lit {
1326                                                         if i.base10_digits().parse::<usize>().unwrap() >= 32 {
1327                                                                 let mut buf = Vec::new();
1328                                                                 self.write_rust_type(&mut buf, generics, &a.elem);
1329                                                                 let ty = String::from_utf8(buf).unwrap();
1330                                                                 ty == "u8"
1331                                                         } else {
1332                                                                 // Blindly assume that if we're trying to create an empty value for an
1333                                                                 // array < 32 entries that all-0s may be a valid state.
1334                                                                 unimplemented!();
1335                                                         }
1336                                                 } else { unimplemented!(); }
1337                                         } else { unimplemented!(); }
1338                                 },
1339                                 syn::Type::Path(p) => {
1340                                         if let Some(resolved) = self.maybe_resolve_path(&p.path, generics) {
1341                                                 if self.c_type_has_inner_from_path(&resolved) { return true; }
1342                                                 if self.is_primitive(&resolved) { return false; }
1343                                                 if self.c_type_from_path(&resolved, false, false).is_some() { true } else { false }
1344                                         } else { true }
1345                                 },
1346                                 syn::Type::Tuple(_) => false,
1347                                 _ => unimplemented!(),
1348                         }
1349                 } else { false }
1350         }
1351         /// Returns true if the path is a "transparent" container, ie an Option or a container which does
1352         /// not require a generated continer class.
1353         pub fn is_path_transparent_container(&self, full_path: &syn::Path, generics: Option<&GenericTypes>, is_ref: bool) -> bool {
1354                 let inner_iter = match &full_path.segments.last().unwrap().arguments {
1355                         syn::PathArguments::None => return false,
1356                         syn::PathArguments::AngleBracketed(args) => args.args.iter().map(|arg| {
1357                                 if let syn::GenericArgument::Type(ref ty) = arg {
1358                                         ty
1359                                 } else { unimplemented!() }
1360                         }),
1361                         syn::PathArguments::Parenthesized(_) => unimplemented!(),
1362                 };
1363                 self.is_transparent_container(&self.resolve_path(full_path, generics), is_ref, inner_iter, generics)
1364         }
1365         /// Returns true if this is a known, supported, non-transparent container.
1366         fn is_known_container(&self, full_path: &str, is_ref: bool) -> bool {
1367                 (full_path == "Result" && !is_ref) || (full_path == "Vec" && !is_ref) || full_path.ends_with("Tuple") || full_path == "Option"
1368         }
1369         fn to_c_conversion_container_new_var<'b>(&self, generics: Option<&GenericTypes>, full_path: &str, is_ref: bool, single_contained: Option<&syn::Type>, var_name: &syn::Ident, var_access: &str)
1370                         // Returns prefix + Vec<(prefix, var-name-to-inline-convert)> + suffix
1371                         // expecting one element in the vec per generic type, each of which is inline-converted
1372                         -> Option<(&'b str, Vec<(String, String)>, &'b str, ContainerPrefixLocation)> {
1373                 match full_path {
1374                         "Result" if !is_ref => {
1375                                 Some(("match ",
1376                                                 vec![(" { Ok(mut o) => crate::c_types::CResultTempl::ok(".to_string(), "o".to_string()),
1377                                                         (").into(), Err(mut e) => crate::c_types::CResultTempl::err(".to_string(), "e".to_string())],
1378                                                 ").into() }", ContainerPrefixLocation::PerConv))
1379                         },
1380                         "Vec" => {
1381                                 if is_ref {
1382                                         // We should only get here if the single contained has an inner
1383                                         assert!(self.c_type_has_inner(single_contained.unwrap()));
1384                                 }
1385                                 Some(("Vec::new(); for mut item in ", vec![(format!(".drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
1386                         },
1387                         "Slice" => {
1388                                 if let Some(syn::Type::Reference(_)) = single_contained {
1389                                         Some(("Vec::new(); for item in ", vec![(format!(".iter() {{ local_{}.push(", var_name), "(*item)".to_string())], "); }", ContainerPrefixLocation::PerConv))
1390                                 } else {
1391                                         Some(("Vec::new(); for item in ", vec![(format!(".iter() {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
1392                                 }
1393                         },
1394                         "Option" => {
1395                                 let mut is_contained_ref = false;
1396                                 let contained_struct = if let Some(syn::Type::Path(p)) = single_contained {
1397                                         Some(self.resolve_path(&p.path, generics))
1398                                 } else if let Some(syn::Type::Reference(r)) = single_contained {
1399                                         is_contained_ref = true;
1400                                         if let syn::Type::Path(p) = &*r.elem {
1401                                                 Some(self.resolve_path(&p.path, generics))
1402                                         } else { None }
1403                                 } else { None };
1404                                 if let Some(inner_path) = contained_struct {
1405                                         let only_contained_has_inner = self.c_type_has_inner_from_path(&inner_path);
1406                                         if self.c_type_has_inner_from_path(&inner_path) {
1407                                                 let is_inner_ref = if let Some(syn::Type::Reference(_)) = single_contained { true } else { false };
1408                                                 if is_ref {
1409                                                         return Some(("if ", vec![
1410                                                                 (".is_none() { core::ptr::null() } else { ObjOps::nonnull_ptr_to_inner(".to_owned(),
1411                                                                         format!("({}{}.unwrap())", var_access, if is_inner_ref { "" } else { ".as_ref()" }))
1412                                                                 ], ") }", ContainerPrefixLocation::OutsideConv));
1413                                                 } else {
1414                                                         return Some(("if ", vec![
1415                                                                 (".is_none() { core::ptr::null_mut() } else { ".to_owned(), format!("({}.unwrap())", var_access))
1416                                                                 ], " }", ContainerPrefixLocation::OutsideConv));
1417                                                 }
1418                                         } else if self.is_primitive(&inner_path) || self.c_type_from_path(&inner_path, false, false).is_none() {
1419                                                 if self.is_primitive(&inner_path) || (!is_contained_ref && !is_ref) || only_contained_has_inner {
1420                                                         let inner_name = self.get_c_mangled_container_type(vec![single_contained.unwrap()], generics, "Option").unwrap();
1421                                                         return Some(("if ", vec![
1422                                                                 (format!(".is_none() {{ {}::None }} else {{ {}::Some(", inner_name, inner_name),
1423                                                                  format!("{}.unwrap()", var_access))
1424                                                                 ], ") }", ContainerPrefixLocation::PerConv));
1425                                                 } else {
1426                                                         let inner_name = self.get_c_mangled_container_type(vec![single_contained.unwrap()], generics, "Option").unwrap();
1427                                                         return Some(("if ", vec![
1428                                                                 (format!(".is_none() {{ {}::None }} else {{ {}::Some(/* WARNING: CLONING CONVERSION HERE! &Option<Enum> is otherwise un-expressable. */", inner_name, inner_name),
1429                                                                  format!("{}.clone().unwrap()", var_access))
1430                                                                 ], ") }", ContainerPrefixLocation::PerConv));
1431                                                 }
1432                                         } else {
1433                                                 // If c_type_from_path is some (ie there's a manual mapping for the inner
1434                                                 // type), lean on write_empty_rust_val, below.
1435                                         }
1436                                 }
1437                                 if let Some(t) = single_contained {
1438                                         if let syn::Type::Tuple(syn::TypeTuple { elems, .. }) = t {
1439                                                 assert!(elems.is_empty());
1440                                                 let inner_name = self.get_c_mangled_container_type(vec![single_contained.unwrap()], generics, "Option").unwrap();
1441                                                 return Some(("if ", vec![
1442                                                         (format!(".is_none() {{ {}::None }} else {{ {}::Some /*",
1443                                                                 inner_name, inner_name), format!(""))
1444                                                         ], " */}", ContainerPrefixLocation::PerConv));
1445                                         }
1446                                         if let syn::Type::Reference(syn::TypeReference { elem, .. }) = t {
1447                                                 if let syn::Type::Slice(_) = &**elem {
1448                                                         return Some(("if ", vec![
1449                                                                         (".is_none() { SmartPtr::null() } else { SmartPtr::from_obj(".to_string(),
1450                                                                          format!("({}.unwrap())", var_access))
1451                                                                 ], ") }", ContainerPrefixLocation::PerConv));
1452                                                 }
1453                                         }
1454                                         let mut v = Vec::new();
1455                                         self.write_empty_rust_val(generics, &mut v, t);
1456                                         let s = String::from_utf8(v).unwrap();
1457                                         return Some(("if ", vec![
1458                                                 (format!(".is_none() {{ {} }} else {{ ", s), format!("({}.unwrap())", var_access))
1459                                                 ], " }", ContainerPrefixLocation::PerConv));
1460                                 } else { unreachable!(); }
1461                         },
1462                         _ => None,
1463                 }
1464         }
1465
1466         /// only_contained_has_inner implies that there is only one contained element in the container
1467         /// and it has an inner field (ie is an "opaque" type we've defined).
1468         fn from_c_conversion_container_new_var<'b>(&self, generics: Option<&GenericTypes>, full_path: &str, is_ref: bool, single_contained: Option<&syn::Type>, var_name: &syn::Ident, var_access: &str)
1469                         // Returns prefix + Vec<(prefix, var-name-to-inline-convert)> + suffix
1470                         // expecting one element in the vec per generic type, each of which is inline-converted
1471                         -> Option<(&'b str, Vec<(String, String)>, &'b str, ContainerPrefixLocation)> {
1472                 let mut only_contained_has_inner = false;
1473                 let only_contained_resolved = if let Some(syn::Type::Path(p)) = single_contained {
1474                         let res = self.resolve_path(&p.path, generics);
1475                         only_contained_has_inner = self.c_type_has_inner_from_path(&res);
1476                         Some(res)
1477                 } else { None };
1478                 match full_path {
1479                         "Result" if !is_ref => {
1480                                 Some(("match ",
1481                                                 vec![(".result_ok { true => Ok(".to_string(), format!("(*unsafe {{ Box::from_raw(<*mut _>::take_ptr(&mut {}.contents.result)) }})", var_access)),
1482                                                      ("), false => Err(".to_string(), format!("(*unsafe {{ Box::from_raw(<*mut _>::take_ptr(&mut {}.contents.err)) }})", var_access))],
1483                                                 ")}", ContainerPrefixLocation::PerConv))
1484                         },
1485                         "Slice" if is_ref && only_contained_has_inner => {
1486                                 Some(("Vec::new(); for mut item in ", vec![(format!(".as_slice().iter() {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
1487                         },
1488                         "Vec"|"Slice" => {
1489                                 Some(("Vec::new(); for mut item in ", vec![(format!(".into_rust().drain(..) {{ local_{}.push(", var_name), "item".to_string())], "); }", ContainerPrefixLocation::PerConv))
1490                         },
1491                         "Option" => {
1492                                 if let Some(resolved) = only_contained_resolved {
1493                                         if self.is_primitive(&resolved) {
1494                                                 return Some(("if ", vec![(".is_some() { Some(".to_string(), format!("{}.take()", var_access))], ") } else { None }", ContainerPrefixLocation::NoPrefix))
1495                                         } else if only_contained_has_inner {
1496                                                 if is_ref {
1497                                                         return Some(("if ", vec![(".inner.is_null() { None } else { Some((*".to_string(), format!("{}", var_access))], ").clone()) }", ContainerPrefixLocation::PerConv))
1498                                                 } else {
1499                                                         return Some(("if ", vec![(".inner.is_null() { None } else { Some(".to_string(), format!("{}", var_access))], ") }", ContainerPrefixLocation::PerConv));
1500                                                 }
1501                                         }
1502                                 }
1503
1504                                 if let Some(t) = single_contained {
1505                                         match t {
1506                                                 syn::Type::Reference(_)|syn::Type::Path(_)|syn::Type::Slice(_) => {
1507                                                         let mut v = Vec::new();
1508                                                         let ret_ref = self.write_empty_rust_val_check_suffix(generics, &mut v, t);
1509                                                         let s = String::from_utf8(v).unwrap();
1510                                                         match ret_ref {
1511                                                                 EmptyValExpectedTy::ReferenceAsPointer =>
1512                                                                         return Some(("if ", vec![
1513                                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("unsafe {{ &mut *{} }}", var_access))
1514                                                                         ], ") }", ContainerPrefixLocation::NoPrefix)),
1515                                                                 EmptyValExpectedTy::OptionType =>
1516                                                                         return Some(("{ /* ", vec![
1517                                                                                 (format!("*/ let {}_opt = {};", var_name, var_access),
1518                                                                                 format!("}} if {}_opt{} {{ None }} else {{ Some({{ {}_opt.take()", var_name, s, var_name))
1519                                                                         ], ") } }", ContainerPrefixLocation::PerConv)),
1520                                                                 EmptyValExpectedTy::NonPointer =>
1521                                                                         return Some(("if ", vec![
1522                                                                                 (format!("{} {{ None }} else {{ Some(", s), format!("{}", var_access))
1523                                                                         ], ") }", ContainerPrefixLocation::PerConv)),
1524                                                         }
1525                                                 },
1526                                                 syn::Type::Tuple(_) => {
1527                                                         return Some(("if ", vec![(".is_some() { Some(".to_string(), format!("{}.take()", var_access))], ") } else { None }", ContainerPrefixLocation::PerConv))
1528                                                 },
1529                                                 _ => unimplemented!(),
1530                                         }
1531                                 } else { unreachable!(); }
1532                         },
1533                         _ => None,
1534                 }
1535         }
1536
1537         /// Constructs a reference to the given type, possibly tweaking the type if relevant to make it
1538         /// convertable to C.
1539         pub fn create_ownable_reference(&self, t: &syn::Type, generics: Option<&GenericTypes>) -> Option<syn::Type> {
1540                 let default_value = Some(syn::Type::Reference(syn::TypeReference {
1541                         and_token: syn::Token!(&)(Span::call_site()), lifetime: None, mutability: None,
1542                         elem: Box::new(t.clone()) }));
1543                 match generics.resolve_type(t) {
1544                         syn::Type::Path(p) => {
1545                                 if let Some(resolved_path) = self.maybe_resolve_path(&p.path, generics) {
1546                                         if resolved_path != "Vec" { return default_value; }
1547                                         if p.path.segments.len() != 1 { unimplemented!(); }
1548                                         let only_seg = p.path.segments.iter().next().unwrap();
1549                                         if let syn::PathArguments::AngleBracketed(args) = &only_seg.arguments {
1550                                                 if args.args.len() != 1 { unimplemented!(); }
1551                                                 let inner_arg = args.args.iter().next().unwrap();
1552                                                 if let syn::GenericArgument::Type(ty) = &inner_arg {
1553                                                         let mut can_create = self.c_type_has_inner(&ty);
1554                                                         if let syn::Type::Path(inner) = ty {
1555                                                                 if inner.path.segments.len() == 1 &&
1556                                                                                 format!("{}", inner.path.segments[0].ident) == "Vec" {
1557                                                                         can_create = true;
1558                                                                 }
1559                                                         }
1560                                                         if !can_create { return default_value; }
1561                                                         if let Some(inner_ty) = self.create_ownable_reference(&ty, generics) {
1562                                                                 return Some(syn::Type::Reference(syn::TypeReference {
1563                                                                         and_token: syn::Token![&](Span::call_site()),
1564                                                                         lifetime: None,
1565                                                                         mutability: None,
1566                                                                         elem: Box::new(syn::Type::Slice(syn::TypeSlice {
1567                                                                                 bracket_token: syn::token::Bracket { span: Span::call_site() },
1568                                                                                 elem: Box::new(inner_ty)
1569                                                                         }))
1570                                                                 }));
1571                                                         } else { return default_value; }
1572                                                 } else { unimplemented!(); }
1573                                         } else { unimplemented!(); }
1574                                 } else { return None; }
1575                         },
1576                         _ => default_value,
1577                 }
1578         }
1579
1580         // *************************************************
1581         // *** Type definition during main.rs processing ***
1582         // *************************************************
1583
1584         /// Returns true if the object at the given path is mapped as X { inner: *mut origX, .. }.
1585         pub fn c_type_has_inner_from_path(&self, full_path: &str) -> bool {
1586                 self.crate_types.opaques.get(full_path).is_some()
1587         }
1588
1589         /// Returns true if the object at the given path is mapped as X { inner: *mut origX, .. }.
1590         pub fn c_type_has_inner(&self, ty: &syn::Type) -> bool {
1591                 match ty {
1592                         syn::Type::Path(p) => {
1593                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, None) {
1594                                         self.c_type_has_inner_from_path(&full_path)
1595                                 } else { false }
1596                         },
1597                         syn::Type::Reference(r) => {
1598                                 self.c_type_has_inner(&*r.elem)
1599                         },
1600                         _ => false,
1601                 }
1602         }
1603
1604         pub fn maybe_resolve_ident(&self, id: &syn::Ident) -> Option<String> {
1605                 self.types.maybe_resolve_ident(id)
1606         }
1607
1608         pub fn maybe_resolve_path(&self, p_arg: &syn::Path, generics: Option<&GenericTypes>) -> Option<String> {
1609                 self.types.maybe_resolve_path(p_arg, generics)
1610         }
1611         pub fn resolve_path(&self, p: &syn::Path, generics: Option<&GenericTypes>) -> String {
1612                 self.maybe_resolve_path(p, generics).unwrap()
1613         }
1614
1615         // ***********************************
1616         // *** Original Rust Type Printing ***
1617         // ***********************************
1618
1619         fn in_rust_prelude(resolved_path: &str) -> bool {
1620                 match resolved_path {
1621                         "Vec" => true,
1622                         "Result" => true,
1623                         "Option" => true,
1624                         _ => false,
1625                 }
1626         }
1627
1628         fn write_rust_path<W: std::io::Write>(&self, w: &mut W, generics_resolver: Option<&GenericTypes>, path: &syn::Path) {
1629                 if let Some(resolved) = self.maybe_resolve_path(&path, generics_resolver) {
1630                         if self.is_primitive(&resolved) {
1631                                 write!(w, "{}", path.get_ident().unwrap()).unwrap();
1632                         } else {
1633                                 // TODO: We should have a generic "is from a dependency" check here instead of
1634                                 // checking for "bitcoin" explicitly.
1635                                 if resolved.starts_with("bitcoin::") || Self::in_rust_prelude(&resolved) {
1636                                         write!(w, "{}", resolved).unwrap();
1637                                 // If we're printing a generic argument, it needs to reference the crate, otherwise
1638                                 // the original crate:
1639                                 } else if self.maybe_resolve_path(&path, None).as_ref() == Some(&resolved) {
1640                                         write!(w, "{}", self.real_rust_type_mapping(&resolved)).unwrap();
1641                                 } else {
1642                                         write!(w, "crate::{}", resolved).unwrap();
1643                                 }
1644                         }
1645                         if let syn::PathArguments::AngleBracketed(args) = &path.segments.iter().last().unwrap().arguments {
1646                                 self.write_rust_generic_arg(w, generics_resolver, args.args.iter());
1647                         }
1648                 } else {
1649                         if path.leading_colon.is_some() {
1650                                 write!(w, "::").unwrap();
1651                         }
1652                         for (idx, seg) in path.segments.iter().enumerate() {
1653                                 if idx != 0 { write!(w, "::").unwrap(); }
1654                                 write!(w, "{}", seg.ident).unwrap();
1655                                 if let syn::PathArguments::AngleBracketed(args) = &seg.arguments {
1656                                         self.write_rust_generic_arg(w, generics_resolver, args.args.iter());
1657                                 }
1658                         }
1659                 }
1660         }
1661         pub fn write_rust_generic_param<'b, W: std::io::Write>(&self, w: &mut W, generics_resolver: Option<&GenericTypes>, generics: impl Iterator<Item=&'b syn::GenericParam>) {
1662                 let mut had_params = false;
1663                 for (idx, arg) in generics.enumerate() {
1664                         if idx != 0 { write!(w, ", ").unwrap(); } else { write!(w, "<").unwrap(); }
1665                         had_params = true;
1666                         match arg {
1667                                 syn::GenericParam::Lifetime(lt) => write!(w, "'{}", lt.lifetime.ident).unwrap(),
1668                                 syn::GenericParam::Type(t) => {
1669                                         write!(w, "{}", t.ident).unwrap();
1670                                         if t.colon_token.is_some() { write!(w, ":").unwrap(); }
1671                                         for (idx, bound) in t.bounds.iter().enumerate() {
1672                                                 if idx != 0 { write!(w, " + ").unwrap(); }
1673                                                 match bound {
1674                                                         syn::TypeParamBound::Trait(tb) => {
1675                                                                 if tb.paren_token.is_some() || tb.lifetimes.is_some() { unimplemented!(); }
1676                                                                 self.write_rust_path(w, generics_resolver, &tb.path);
1677                                                         },
1678                                                         _ => unimplemented!(),
1679                                                 }
1680                                         }
1681                                         if t.eq_token.is_some() || t.default.is_some() { unimplemented!(); }
1682                                 },
1683                                 _ => unimplemented!(),
1684                         }
1685                 }
1686                 if had_params { write!(w, ">").unwrap(); }
1687         }
1688
1689         pub fn write_rust_generic_arg<'b, W: std::io::Write>(&self, w: &mut W, generics_resolver: Option<&GenericTypes>, generics: impl Iterator<Item=&'b syn::GenericArgument>) {
1690                 write!(w, "<").unwrap();
1691                 for (idx, arg) in generics.enumerate() {
1692                         if idx != 0 { write!(w, ", ").unwrap(); }
1693                         match arg {
1694                                 syn::GenericArgument::Type(t) => self.write_rust_type(w, generics_resolver, t),
1695                                 _ => unimplemented!(),
1696                         }
1697                 }
1698                 write!(w, ">").unwrap();
1699         }
1700         pub fn write_rust_type<W: std::io::Write>(&self, w: &mut W, generics: Option<&GenericTypes>, t: &syn::Type) {
1701                 match generics.resolve_type(t) {
1702                         syn::Type::Path(p) => {
1703                                 if p.qself.is_some() {
1704                                         unimplemented!();
1705                                 }
1706                                 self.write_rust_path(w, generics, &p.path);
1707                         },
1708                         syn::Type::Reference(r) => {
1709                                 write!(w, "&").unwrap();
1710                                 if let Some(lft) = &r.lifetime {
1711                                         write!(w, "'{} ", lft.ident).unwrap();
1712                                 }
1713                                 if r.mutability.is_some() {
1714                                         write!(w, "mut ").unwrap();
1715                                 }
1716                                 self.write_rust_type(w, generics, &*r.elem);
1717                         },
1718                         syn::Type::Array(a) => {
1719                                 write!(w, "[").unwrap();
1720                                 self.write_rust_type(w, generics, &a.elem);
1721                                 if let syn::Expr::Lit(l) = &a.len {
1722                                         if let syn::Lit::Int(i) = &l.lit {
1723                                                 write!(w, "; {}]", i).unwrap();
1724                                         } else { unimplemented!(); }
1725                                 } else { unimplemented!(); }
1726                         }
1727                         syn::Type::Slice(s) => {
1728                                 write!(w, "[").unwrap();
1729                                 self.write_rust_type(w, generics, &s.elem);
1730                                 write!(w, "]").unwrap();
1731                         },
1732                         syn::Type::Tuple(s) => {
1733                                 write!(w, "(").unwrap();
1734                                 for (idx, t) in s.elems.iter().enumerate() {
1735                                         if idx != 0 { write!(w, ", ").unwrap(); }
1736                                         self.write_rust_type(w, generics, &t);
1737                                 }
1738                                 write!(w, ")").unwrap();
1739                         },
1740                         _ => unimplemented!(),
1741                 }
1742         }
1743
1744         /// Prints a constructor for something which is "uninitialized" (but obviously not actually
1745         /// unint'd memory).
1746         pub fn write_empty_rust_val<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type) {
1747                 match t {
1748                         syn::Type::Reference(r) => {
1749                                 self.write_empty_rust_val(generics, w, &*r.elem)
1750                         },
1751                         syn::Type::Path(p) => {
1752                                 let resolved = self.resolve_path(&p.path, generics);
1753                                 if self.crate_types.opaques.get(&resolved).is_some() {
1754                                         write!(w, "crate::{} {{ inner: core::ptr::null_mut(), is_owned: true }}", resolved).unwrap();
1755                                 } else {
1756                                         // Assume its a manually-mapped C type, where we can just define an null() fn
1757                                         write!(w, "{}::null()", self.c_type_from_path(&resolved, false, false).unwrap()).unwrap();
1758                                 }
1759                         },
1760                         syn::Type::Array(a) => {
1761                                 if let syn::Expr::Lit(l) = &a.len {
1762                                         if let syn::Lit::Int(i) = &l.lit {
1763                                                 if i.base10_digits().parse::<usize>().unwrap() < 32 {
1764                                                         // Blindly assume that if we're trying to create an empty value for an
1765                                                         // array < 32 entries that all-0s may be a valid state.
1766                                                         unimplemented!();
1767                                                 }
1768                                                 let arrty = format!("[u8; {}]", i.base10_digits());
1769                                                 write!(w, "{}", self.to_c_conversion_inline_prefix_from_path(&arrty, false, false).unwrap()).unwrap();
1770                                                 write!(w, "[0; {}]", i.base10_digits()).unwrap();
1771                                                 write!(w, "{}", self.to_c_conversion_inline_suffix_from_path(&arrty, false, false).unwrap()).unwrap();
1772                                         } else { unimplemented!(); }
1773                                 } else { unimplemented!(); }
1774                         }
1775                         _ => unimplemented!(),
1776                 }
1777         }
1778
1779         fn is_real_type_array(&self, resolved_type: &str) -> Option<syn::Type> {
1780                 if let Some(real_ty) = self.c_type_from_path(&resolved_type, true, false) {
1781                         if real_ty.ends_with("]") && real_ty.starts_with("*const [u8; ") {
1782                                 let mut split = real_ty.split("; ");
1783                                 split.next().unwrap();
1784                                 let tail_str = split.next().unwrap();
1785                                 assert!(split.next().is_none());
1786                                 let len = usize::from_str_radix(&tail_str[..tail_str.len() - 1], 10).unwrap();
1787                                 Some(parse_quote!([u8; #len]))
1788                         } else { None }
1789                 } else { None }
1790         }
1791
1792         /// Prints a suffix to determine if a variable is empty (ie was set by write_empty_rust_val).
1793         /// See EmptyValExpectedTy for information on return types.
1794         fn write_empty_rust_val_check_suffix<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type) -> EmptyValExpectedTy {
1795                 match t {
1796                         syn::Type::Reference(r) => {
1797                                 return self.write_empty_rust_val_check_suffix(generics, w, &*r.elem);
1798                         },
1799                         syn::Type::Path(p) => {
1800                                 let resolved = self.resolve_path(&p.path, generics);
1801                                 if let Some(arr_ty) = self.is_real_type_array(&resolved) {
1802                                         write!(w, ".data").unwrap();
1803                                         return self.write_empty_rust_val_check_suffix(generics, w, &arr_ty);
1804                                 }
1805                                 if self.crate_types.opaques.get(&resolved).is_some() {
1806                                         write!(w, ".inner.is_null()").unwrap();
1807                                         EmptyValExpectedTy::NonPointer
1808                                 } else {
1809                                         if let Some(suffix) = self.empty_val_check_suffix_from_path(&resolved) {
1810                                                 write!(w, "{}", suffix).unwrap();
1811                                                 // We may eventually need to allow empty_val_check_suffix_from_path to specify if we need a deref or not
1812                                                 EmptyValExpectedTy::NonPointer
1813                                         } else {
1814                                                 write!(w, ".is_none()").unwrap();
1815                                                 EmptyValExpectedTy::OptionType
1816                                         }
1817                                 }
1818                         },
1819                         syn::Type::Array(a) => {
1820                                 if let syn::Expr::Lit(l) = &a.len {
1821                                         if let syn::Lit::Int(i) = &l.lit {
1822                                                 write!(w, " == [0; {}]", i.base10_digits()).unwrap();
1823                                                 EmptyValExpectedTy::NonPointer
1824                                         } else { unimplemented!(); }
1825                                 } else { unimplemented!(); }
1826                         },
1827                         syn::Type::Slice(_) => {
1828                                 // Option<[]> always implies that we want to treat len() == 0 differently from
1829                                 // None, so we always map an Option<[]> into a pointer.
1830                                 write!(w, " == core::ptr::null_mut()").unwrap();
1831                                 EmptyValExpectedTy::ReferenceAsPointer
1832                         },
1833                         _ => unimplemented!(),
1834                 }
1835         }
1836
1837         /// Prints a suffix to determine if a variable is empty (ie was set by write_empty_rust_val).
1838         pub fn write_empty_rust_val_check<W: std::io::Write>(&self, generics: Option<&GenericTypes>, w: &mut W, t: &syn::Type, var_access: &str) {
1839                 match t {
1840                         syn::Type::Reference(r) => {
1841                                 self.write_empty_rust_val_check(generics, w, &*r.elem, var_access);
1842                         },
1843                         syn::Type::Path(_) => {
1844                                 write!(w, "{}", var_access).unwrap();
1845                                 self.write_empty_rust_val_check_suffix(generics, w, t);
1846                         },
1847                         syn::Type::Array(a) => {
1848                                 if let syn::Expr::Lit(l) = &a.len {
1849                                         if let syn::Lit::Int(i) = &l.lit {
1850                                                 let arrty = format!("[u8; {}]", i.base10_digits());
1851                                                 // We don't (yet) support a new-var conversion here.
1852                                                 assert!(self.from_c_conversion_new_var_from_path(&arrty, false).is_none());
1853                                                 write!(w, "{}{}{}",
1854                                                         self.from_c_conversion_prefix_from_path(&arrty, false).unwrap(),
1855                                                         var_access,
1856                                                         self.from_c_conversion_suffix_from_path(&arrty, false).unwrap()).unwrap();
1857                                                 self.write_empty_rust_val_check_suffix(generics, w, t);
1858                                         } else { unimplemented!(); }
1859                                 } else { unimplemented!(); }
1860                         }
1861                         _ => unimplemented!(),
1862                 }
1863         }
1864
1865         // ********************************
1866         // *** Type conversion printing ***
1867         // ********************************
1868
1869         /// Returns true we if can just skip passing this to C entirely
1870         pub fn skip_arg(&self, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
1871                 match t {
1872                         syn::Type::Path(p) => {
1873                                 if p.qself.is_some() { unimplemented!(); }
1874                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
1875                                         self.skip_path(&full_path)
1876                                 } else { false }
1877                         },
1878                         syn::Type::Reference(r) => {
1879                                 self.skip_arg(&*r.elem, generics)
1880                         },
1881                         _ => false,
1882                 }
1883         }
1884         pub fn no_arg_to_rust<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
1885                 match t {
1886                         syn::Type::Path(p) => {
1887                                 if p.qself.is_some() { unimplemented!(); }
1888                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
1889                                         write!(w, "{}", self.no_arg_path_to_rust(&full_path)).unwrap();
1890                                 }
1891                         },
1892                         syn::Type::Reference(r) => {
1893                                 self.no_arg_to_rust(w, &*r.elem, generics);
1894                         },
1895                         _ => {},
1896                 }
1897         }
1898
1899         fn write_conversion_inline_intern<W: std::io::Write,
1900                         LP: Fn(&str, bool, bool) -> Option<String>, DL: Fn(&mut W, &DeclType, &str, bool, bool), SC: Fn(bool, Option<&str>) -> String>
1901                         (&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool,
1902                          tupleconv: &str, prefix: bool, sliceconv: SC, path_lookup: LP, decl_lookup: DL) {
1903                 match generics.resolve_type(t) {
1904                         syn::Type::Reference(r) => {
1905                                 self.write_conversion_inline_intern(w, &*r.elem, generics, true, r.mutability.is_some(),
1906                                         ptr_for_ref, tupleconv, prefix, sliceconv, path_lookup, decl_lookup);
1907                         },
1908                         syn::Type::Path(p) => {
1909                                 if p.qself.is_some() {
1910                                         unimplemented!();
1911                                 }
1912
1913                                 let resolved_path = self.resolve_path(&p.path, generics);
1914                                 if let Some(aliased_type) = self.crate_types.type_aliases.get(&resolved_path) {
1915                                         return self.write_conversion_inline_intern(w, aliased_type, None, is_ref, is_mut, ptr_for_ref, tupleconv, prefix, sliceconv, path_lookup, decl_lookup);
1916                                 } else if self.is_primitive(&resolved_path) {
1917                                         if is_ref && prefix {
1918                                                 write!(w, "*").unwrap();
1919                                         }
1920                                 } else if let Some(c_type) = path_lookup(&resolved_path, is_ref, ptr_for_ref) {
1921                                         write!(w, "{}", c_type).unwrap();
1922                                 } else if let Some((_, generics)) = self.crate_types.opaques.get(&resolved_path) {
1923                                         decl_lookup(w, &DeclType::StructImported { generics: &generics }, &resolved_path, is_ref, is_mut);
1924                                 } else if self.crate_types.mirrored_enums.get(&resolved_path).is_some() {
1925                                         decl_lookup(w, &DeclType::MirroredEnum, &resolved_path, is_ref, is_mut);
1926                                 } else if let Some(t) = self.crate_types.traits.get(&resolved_path) {
1927                                         decl_lookup(w, &DeclType::Trait(t), &resolved_path, is_ref, is_mut);
1928                                 } else if let Some(ident) = single_ident_generic_path_to_ident(&p.path) {
1929                                         if let Some(decl_type) = self.types.maybe_resolve_declared(ident) {
1930                                                 decl_lookup(w, decl_type, &self.maybe_resolve_ident(ident).unwrap(), is_ref, is_mut);
1931                                         } else { unimplemented!(); }
1932                                 } else { unimplemented!(); }
1933                         },
1934                         syn::Type::Array(a) => {
1935                                 // We assume all arrays contain only [int_literal; X]s.
1936                                 // This may result in some outputs not compiling.
1937                                 if let syn::Expr::Lit(l) = &a.len {
1938                                         if let syn::Lit::Int(i) = &l.lit {
1939                                                 write!(w, "{}", path_lookup(&format!("[u8; {}]", i.base10_digits()), is_ref, ptr_for_ref).unwrap()).unwrap();
1940                                         } else { unimplemented!(); }
1941                                 } else { unimplemented!(); }
1942                         },
1943                         syn::Type::Slice(s) => {
1944                                 // We assume all slices contain only literals or references.
1945                                 // This may result in some outputs not compiling.
1946                                 if let syn::Type::Path(p) = &*s.elem {
1947                                         let resolved = self.resolve_path(&p.path, generics);
1948                                         if self.is_primitive(&resolved) {
1949                                                 write!(w, "{}", path_lookup("[u8]", is_ref, ptr_for_ref).unwrap()).unwrap();
1950                                         } else {
1951                                                 write!(w, "{}", sliceconv(true, None)).unwrap();
1952                                         }
1953                                 } else if let syn::Type::Reference(r) = &*s.elem {
1954                                         if let syn::Type::Path(p) = &*r.elem {
1955                                                 write!(w, "{}", sliceconv(self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)), None)).unwrap();
1956                                         } else if let syn::Type::Slice(_) = &*r.elem {
1957                                                 write!(w, "{}", sliceconv(false, None)).unwrap();
1958                                         } else { unimplemented!(); }
1959                                 } else if let syn::Type::Tuple(t) = &*s.elem {
1960                                         assert!(!t.elems.is_empty());
1961                                         if prefix {
1962                                                 write!(w, "{}", sliceconv(false, None)).unwrap();
1963                                         } else {
1964                                                 let mut needs_map = false;
1965                                                 for e in t.elems.iter() {
1966                                                         if let syn::Type::Reference(_) = e {
1967                                                                 needs_map = true;
1968                                                         }
1969                                                 }
1970                                                 if needs_map {
1971                                                         let mut map_str = Vec::new();
1972                                                         write!(&mut map_str, ".map(|(").unwrap();
1973                                                         for i in 0..t.elems.len() {
1974                                                                 write!(&mut map_str, "{}{}", if i != 0 { ", " } else { "" }, ('a' as u8 + i as u8) as char).unwrap();
1975                                                         }
1976                                                         write!(&mut map_str, ")| (").unwrap();
1977                                                         for (idx, e) in t.elems.iter().enumerate() {
1978                                                                 if let syn::Type::Reference(_) = e {
1979                                                                         write!(&mut map_str, "{}{}", if idx != 0 { ", " } else { "" }, (idx as u8 + 'a' as u8) as char).unwrap();
1980                                                                 } else if let syn::Type::Path(_) = e {
1981                                                                         write!(&mut map_str, "{}*{}", if idx != 0 { ", " } else { "" }, (idx as u8 + 'a' as u8) as char).unwrap();
1982                                                                 } else { unimplemented!(); }
1983                                                         }
1984                                                         write!(&mut map_str, "))").unwrap();
1985                                                         write!(w, "{}", sliceconv(false, Some(&String::from_utf8(map_str).unwrap()))).unwrap();
1986                                                 } else {
1987                                                         write!(w, "{}", sliceconv(false, None)).unwrap();
1988                                                 }
1989                                         }
1990                                 } else { unimplemented!(); }
1991                         },
1992                         syn::Type::Tuple(t) => {
1993                                 if t.elems.is_empty() {
1994                                         // cbindgen has poor support for (), see, eg https://github.com/eqrion/cbindgen/issues/527
1995                                         // so work around it by just pretending its a 0u8
1996                                         write!(w, "{}", tupleconv).unwrap();
1997                                 } else {
1998                                         if prefix { write!(w, "local_").unwrap(); }
1999                                 }
2000                         },
2001                         _ => unimplemented!(),
2002                 }
2003         }
2004
2005         fn write_to_c_conversion_inline_prefix_inner<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, ptr_for_ref: bool, from_ptr: bool) {
2006                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, ptr_for_ref, "() /*", true, |_, _| "local_".to_owned(),
2007                                 |a, b, c| self.to_c_conversion_inline_prefix_from_path(a, b, c),
2008                                 |w, decl_type, decl_path, is_ref, _is_mut| {
2009                                         match decl_type {
2010                                                 DeclType::MirroredEnum if is_ref && ptr_for_ref => write!(w, "crate::{}::from_native(", decl_path).unwrap(),
2011                                                 DeclType::MirroredEnum if is_ref => write!(w, "&crate::{}::from_native(", decl_path).unwrap(),
2012                                                 DeclType::MirroredEnum => write!(w, "crate::{}::native_into(", decl_path).unwrap(),
2013                                                 DeclType::EnumIgnored {..}|DeclType::StructImported {..} if is_ref && from_ptr => {
2014                                                         if !ptr_for_ref { write!(w, "&").unwrap(); }
2015                                                         write!(w, "crate::{} {{ inner: unsafe {{ (", decl_path).unwrap()
2016                                                 },
2017                                                 DeclType::EnumIgnored {..}|DeclType::StructImported {..} if is_ref => {
2018                                                         if !ptr_for_ref { write!(w, "&").unwrap(); }
2019                                                         write!(w, "crate::{} {{ inner: unsafe {{ ObjOps::nonnull_ptr_to_inner((", decl_path).unwrap()
2020                                                 },
2021                                                 DeclType::EnumIgnored {..}|DeclType::StructImported {..} if !is_ref && from_ptr =>
2022                                                         write!(w, "crate::{} {{ inner: ", decl_path).unwrap(),
2023                                                 DeclType::EnumIgnored {..}|DeclType::StructImported {..} if !is_ref =>
2024                                                         write!(w, "crate::{} {{ inner: ObjOps::heap_alloc(", decl_path).unwrap(),
2025                                                 DeclType::Trait(_) if is_ref => write!(w, "").unwrap(),
2026                                                 DeclType::Trait(_) if !is_ref => write!(w, "Into::into(").unwrap(),
2027                                                 _ => panic!("{:?}", decl_path),
2028                                         }
2029                                 });
2030         }
2031         pub fn write_to_c_conversion_inline_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) {
2032                 self.write_to_c_conversion_inline_prefix_inner(w, t, generics, false, ptr_for_ref, false);
2033         }
2034         fn write_to_c_conversion_inline_suffix_inner<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, ptr_for_ref: bool, from_ptr: bool) {
2035                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, ptr_for_ref, "*/", false, |_, _| ".into()".to_owned(),
2036                                 |a, b, c| self.to_c_conversion_inline_suffix_from_path(a, b, c),
2037                                 |w, decl_type, full_path, is_ref, _is_mut| match decl_type {
2038                                         DeclType::MirroredEnum => write!(w, ")").unwrap(),
2039                                         DeclType::EnumIgnored { generics }|DeclType::StructImported { generics } if is_ref => {
2040                                                 write!(w, " as *const {}<", full_path).unwrap();
2041                                                 for param in generics.params.iter() {
2042                                                         if let syn::GenericParam::Lifetime(_) = param {
2043                                                                 write!(w, "'_, ").unwrap();
2044                                                         } else {
2045                                                                 write!(w, "_, ").unwrap();
2046                                                         }
2047                                                 }
2048                                                 if from_ptr {
2049                                                         write!(w, ">) as *mut _ }}, is_owned: false }}").unwrap();
2050                                                 } else {
2051                                                         write!(w, ">) as *mut _) }}, is_owned: false }}").unwrap();
2052                                                 }
2053                                         },
2054                                         DeclType::EnumIgnored {..}|DeclType::StructImported {..} if !is_ref && from_ptr =>
2055                                                 write!(w, ", is_owned: true }}").unwrap(),
2056                                         DeclType::EnumIgnored {..}|DeclType::StructImported {..} if !is_ref => write!(w, "), is_owned: true }}").unwrap(),
2057                                         DeclType::Trait(_) if is_ref => {},
2058                                         DeclType::Trait(_) => {
2059                                                 // This is used when we're converting a concrete Rust type into a C trait
2060                                                 // for use when a Rust trait method returns an associated type.
2061                                                 // Because all of our C traits implement From<RustTypesImplementingTraits>
2062                                                 // we can just call .into() here and be done.
2063                                                 write!(w, ")").unwrap()
2064                                         },
2065                                         _ => unimplemented!(),
2066                                 });
2067         }
2068         pub fn write_to_c_conversion_inline_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) {
2069                 self.write_to_c_conversion_inline_suffix_inner(w, t, generics, false, ptr_for_ref, false);
2070         }
2071
2072         fn write_from_c_conversion_prefix_inner<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, _ptr_for_ref: bool) {
2073                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "() /*", true, |_, _| "&local_".to_owned(),
2074                                 |a, b, _c| self.from_c_conversion_prefix_from_path(a, b),
2075                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
2076                                         DeclType::StructImported {..} if is_ref => write!(w, "").unwrap(),
2077                                         DeclType::StructImported {..} if !is_ref => write!(w, "*unsafe {{ Box::from_raw(").unwrap(),
2078                                         DeclType::MirroredEnum if is_ref => write!(w, "&").unwrap(),
2079                                         DeclType::MirroredEnum => {},
2080                                         DeclType::Trait(_) => {},
2081                                         _ => unimplemented!(),
2082                                 });
2083         }
2084         pub fn write_from_c_conversion_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
2085                 self.write_from_c_conversion_prefix_inner(w, t, generics, false, false);
2086         }
2087         fn write_from_c_conversion_suffix_inner<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, ptr_for_ref: bool) {
2088                 self.write_conversion_inline_intern(w, t, generics, is_ref, false, false, "*/", false,
2089                                 |has_inner, map_str_opt| match (has_inner, map_str_opt) {
2090                                         (false, Some(map_str)) => format!(".iter(){}.collect::<Vec<_>>()[..]", map_str),
2091                                         (false, None) => ".iter().collect::<Vec<_>>()[..]".to_owned(),
2092                                         (true, None) => "[..]".to_owned(),
2093                                         (true, Some(_)) => unreachable!(),
2094                                 },
2095                                 |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
2096                                 |w, decl_type, _full_path, is_ref, is_mut| match decl_type {
2097                                         DeclType::StructImported {..} if is_ref && ptr_for_ref => write!(w, "XXX unimplemented").unwrap(),
2098                                         DeclType::StructImported {..} if is_mut && is_ref => write!(w, ".get_native_mut_ref()").unwrap(),
2099                                         DeclType::StructImported {..} if is_ref => write!(w, ".get_native_ref()").unwrap(),
2100                                         DeclType::StructImported {..} if !is_ref => write!(w, ".take_inner()) }}").unwrap(),
2101                                         DeclType::MirroredEnum if is_ref => write!(w, ".to_native()").unwrap(),
2102                                         DeclType::MirroredEnum => write!(w, ".into_native()").unwrap(),
2103                                         DeclType::Trait(_) => {},
2104                                         _ => unimplemented!(),
2105                                 });
2106         }
2107         pub fn write_from_c_conversion_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
2108                 self.write_from_c_conversion_suffix_inner(w, t, generics, false, false);
2109         }
2110         // Note that compared to the above conversion functions, the following two are generally
2111         // significantly undertested:
2112         pub fn write_from_c_conversion_to_ref_prefix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
2113                 self.write_conversion_inline_intern(w, t, generics, false, false, false, "() /*", true, |_, _| "&local_".to_owned(),
2114                                 |a, b, _c| {
2115                                         if let Some(conv) = self.from_c_conversion_prefix_from_path(a, b) {
2116                                                 Some(format!("&{}", conv))
2117                                         } else { None }
2118                                 },
2119                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
2120                                         DeclType::StructImported {..} if !is_ref => write!(w, "").unwrap(),
2121                                         _ => unimplemented!(),
2122                                 });
2123         }
2124         pub fn write_from_c_conversion_to_ref_suffix<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>) {
2125                 self.write_conversion_inline_intern(w, t, generics, false, false, false, "*/", false,
2126                                 |has_inner, map_str_opt| match (has_inner, map_str_opt) {
2127                                         (false, Some(map_str)) => format!(".iter(){}.collect::<Vec<_>>()[..]", map_str),
2128                                         (false, None) => ".iter().collect::<Vec<_>>()[..]".to_owned(),
2129                                         (true, None) => "[..]".to_owned(),
2130                                         (true, Some(_)) => unreachable!(),
2131                                 },
2132                                 |a, b, _c| self.from_c_conversion_suffix_from_path(a, b),
2133                                 |w, decl_type, _full_path, is_ref, _is_mut| match decl_type {
2134                                         DeclType::StructImported {..} if !is_ref => write!(w, ".get_native_ref()").unwrap(),
2135                                         _ => unimplemented!(),
2136                                 });
2137         }
2138
2139         fn write_conversion_new_var_intern<'b, W: std::io::Write,
2140                 LP: Fn(&str, bool) -> Option<(&str, &str)>,
2141                 LC: Fn(&str, bool, Option<&syn::Type>, &syn::Ident, &str) ->  Option<(&'b str, Vec<(String, String)>, &'b str, ContainerPrefixLocation)>,
2142                 VP: Fn(&mut W, &syn::Type, Option<&GenericTypes>, bool, bool, bool),
2143                 VS: Fn(&mut W, &syn::Type, Option<&GenericTypes>, bool, bool, bool)>
2144                         (&self, w: &mut W, ident: &syn::Ident, var: &str, t: &syn::Type, generics: Option<&GenericTypes>,
2145                          mut is_ref: bool, mut ptr_for_ref: bool, to_c: bool, from_ownable_ref: bool,
2146                          path_lookup: &LP, container_lookup: &LC, var_prefix: &VP, var_suffix: &VS) -> bool {
2147
2148                 macro_rules! convert_container {
2149                         ($container_type: expr, $args_len: expr, $args_iter: expr) => { {
2150                                 // For slices (and Options), we refuse to directly map them as is_ref when they
2151                                 // aren't opaque types containing an inner pointer. This is due to the fact that,
2152                                 // in both cases, the actual higher-level type is non-is_ref.
2153                                 let ty_has_inner = if $args_len == 1 {
2154                                         let ty = $args_iter().next().unwrap();
2155                                         if $container_type == "Slice" && to_c {
2156                                                 // "To C ptr_for_ref" means "return the regular object with is_owned
2157                                                 // set to false", which is totally what we want in a slice if we're about to
2158                                                 // set ty_has_inner.
2159                                                 ptr_for_ref = true;
2160                                         }
2161                                         if let syn::Type::Reference(t) = ty {
2162                                                 if let syn::Type::Path(p) = &*t.elem {
2163                                                         self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
2164                                                 } else { false }
2165                                         } else if let syn::Type::Path(p) = ty {
2166                                                 self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
2167                                         } else { false }
2168                                 } else { true };
2169
2170                                 // Options get a bunch of special handling, since in general we map Option<>al
2171                                 // types into the same C type as non-Option-wrapped types. This ends up being
2172                                 // pretty manual here and most of the below special-cases are for Options.
2173                                 let mut needs_ref_map = false;
2174                                 let mut only_contained_type = None;
2175                                 let mut only_contained_type_nonref = None;
2176                                 let mut only_contained_has_inner = false;
2177                                 let mut contains_slice = false;
2178                                 if $args_len == 1 {
2179                                         only_contained_has_inner = ty_has_inner;
2180                                         let arg = $args_iter().next().unwrap();
2181                                         if let syn::Type::Reference(t) = arg {
2182                                                 only_contained_type = Some(arg);
2183                                                 only_contained_type_nonref = Some(&*t.elem);
2184                                                 if let syn::Type::Path(_) = &*t.elem {
2185                                                         is_ref = true;
2186                                                 } else if let syn::Type::Slice(_) = &*t.elem {
2187                                                         contains_slice = true;
2188                                                 } else { return false; }
2189                                                 // If the inner element contains an inner pointer, we will just use that,
2190                                                 // avoiding the need to map elements to references. Otherwise we'll need to
2191                                                 // do an extra mapping step.
2192                                                 needs_ref_map = !only_contained_has_inner && $container_type == "Option";
2193                                         } else {
2194                                                 only_contained_type = Some(arg);
2195                                                 only_contained_type_nonref = Some(arg);
2196                                         }
2197                                 }
2198
2199                                 if let Some((prefix, conversions, suffix, prefix_location)) = container_lookup(&$container_type, is_ref, only_contained_type, ident, var) {
2200                                         assert_eq!(conversions.len(), $args_len);
2201                                         write!(w, "let mut local_{}{} = ", ident,
2202                                                 if (!to_c && needs_ref_map) || (to_c && $container_type == "Option" && contains_slice) {"_base"} else { "" }).unwrap();
2203                                         if prefix_location == ContainerPrefixLocation::OutsideConv {
2204                                                 var_prefix(w, $args_iter().next().unwrap(), generics, is_ref, ptr_for_ref, true);
2205                                         }
2206                                         write!(w, "{}{}", prefix, var).unwrap();
2207
2208                                         for ((pfx, var_name), (idx, ty)) in conversions.iter().zip($args_iter().enumerate()) {
2209                                                 let mut var = std::io::Cursor::new(Vec::new());
2210                                                 write!(&mut var, "{}", var_name).unwrap();
2211                                                 let var_access = String::from_utf8(var.into_inner()).unwrap();
2212
2213                                                 let conv_ty = if needs_ref_map { only_contained_type_nonref.as_ref().unwrap() } else { ty };
2214
2215                                                 write!(w, "{} {{ ", pfx).unwrap();
2216                                                 let new_var_name = format!("{}_{}", ident, idx);
2217                                                 let new_var = self.write_conversion_new_var_intern(w, &format_ident!("{}", new_var_name),
2218                                                                 &var_access, conv_ty, generics, contains_slice || (is_ref && ty_has_inner), ptr_for_ref,
2219                                                                 to_c, from_ownable_ref, path_lookup, container_lookup, var_prefix, var_suffix);
2220                                                 if new_var { write!(w, " ").unwrap(); }
2221
2222                                                 if prefix_location == ContainerPrefixLocation::PerConv {
2223                                                         var_prefix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
2224                                                 } else if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
2225                                                         write!(w, "ObjOps::heap_alloc(").unwrap();
2226                                                 }
2227
2228                                                 write!(w, "{}{}", if contains_slice && !to_c { "local_" } else { "" }, if new_var { new_var_name } else { var_access }).unwrap();
2229                                                 if prefix_location == ContainerPrefixLocation::PerConv {
2230                                                         var_suffix(w, conv_ty, generics, is_ref && ty_has_inner, ptr_for_ref, false);
2231                                                 } else if !is_ref && !needs_ref_map && to_c && only_contained_has_inner {
2232                                                         write!(w, ")").unwrap();
2233                                                 }
2234                                                 write!(w, " }}").unwrap();
2235                                         }
2236                                         write!(w, "{}", suffix).unwrap();
2237                                         if prefix_location == ContainerPrefixLocation::OutsideConv {
2238                                                 var_suffix(w, $args_iter().next().unwrap(), generics, is_ref, ptr_for_ref, true);
2239                                         }
2240                                         write!(w, ";").unwrap();
2241                                         if !to_c && needs_ref_map {
2242                                                 write!(w, " let mut local_{} = local_{}_base.as_ref()", ident, ident).unwrap();
2243                                                 if contains_slice {
2244                                                         write!(w, ".map(|a| &a[..])").unwrap();
2245                                                 }
2246                                                 write!(w, ";").unwrap();
2247                                         } else if to_c && $container_type == "Option" && contains_slice {
2248                                                 write!(w, " let mut local_{} = *local_{}_base;", ident, ident).unwrap();
2249                                         }
2250                                         return true;
2251                                 }
2252                         } }
2253                 }
2254
2255                 match generics.resolve_type(t) {
2256                         syn::Type::Reference(r) => {
2257                                 if let syn::Type::Slice(_) = &*r.elem {
2258                                         self.write_conversion_new_var_intern(w, ident, var, &*r.elem, generics, is_ref, ptr_for_ref, to_c, from_ownable_ref, path_lookup, container_lookup, var_prefix, var_suffix)
2259                                 } else {
2260                                         self.write_conversion_new_var_intern(w, ident, var, &*r.elem, generics, true, ptr_for_ref, to_c, from_ownable_ref, path_lookup, container_lookup, var_prefix, var_suffix)
2261                                 }
2262                         },
2263                         syn::Type::Path(p) => {
2264                                 if p.qself.is_some() {
2265                                         unimplemented!();
2266                                 }
2267                                 let resolved_path = self.resolve_path(&p.path, generics);
2268                                 if let Some(aliased_type) = self.crate_types.type_aliases.get(&resolved_path) {
2269                                         return self.write_conversion_new_var_intern(w, ident, var, aliased_type, None, is_ref, ptr_for_ref, to_c, from_ownable_ref, path_lookup, container_lookup, var_prefix, var_suffix);
2270                                 }
2271                                 if self.is_known_container(&resolved_path, is_ref) || self.is_path_transparent_container(&p.path, generics, is_ref) {
2272                                         if let syn::PathArguments::AngleBracketed(args) = &p.path.segments.iter().next().unwrap().arguments {
2273                                                 convert_container!(resolved_path, args.args.len(), || args.args.iter().map(|arg| {
2274                                                         if let syn::GenericArgument::Type(ty) = arg {
2275                                                                 generics.resolve_type(ty)
2276                                                         } else { unimplemented!(); }
2277                                                 }));
2278                                         } else { unimplemented!(); }
2279                                 }
2280                                 if self.is_primitive(&resolved_path) {
2281                                         false
2282                                 } else if let Some(ty_ident) = single_ident_generic_path_to_ident(&p.path) {
2283                                         if let Some((prefix, suffix)) = path_lookup(&resolved_path, is_ref) {
2284                                                 write!(w, "let mut local_{} = {}{}{};", ident, prefix, var, suffix).unwrap();
2285                                                 true
2286                                         } else if self.types.maybe_resolve_declared(ty_ident).is_some() {
2287                                                 false
2288                                         } else { false }
2289                                 } else { false }
2290                         },
2291                         syn::Type::Array(_) => {
2292                                 // We assume all arrays contain only primitive types.
2293                                 // This may result in some outputs not compiling.
2294                                 false
2295                         },
2296                         syn::Type::Slice(s) => {
2297                                 if let syn::Type::Path(p) = &*s.elem {
2298                                         let resolved = self.resolve_path(&p.path, generics);
2299                                         if self.is_primitive(&resolved) {
2300                                                 let slice_path = format!("[{}]", resolved);
2301                                                 if let Some((prefix, suffix)) = path_lookup(&slice_path, true) {
2302                                                         write!(w, "let mut local_{} = {}{}{};", ident, prefix, var, suffix).unwrap();
2303                                                         true
2304                                                 } else { false }
2305                                         } else {
2306                                                 let tyref = [&*s.elem];
2307                                                 if to_c {
2308                                                         // If we're converting from a slice to a Vec, assume we can clone the
2309                                                         // elements and clone them into a new Vec first. Next we'll walk the
2310                                                         // new Vec here and convert them to C types.
2311                                                         write!(w, "let mut local_{}_clone = Vec::new(); local_{}_clone.extend_from_slice({}); let mut {} = local_{}_clone; ", ident, ident, ident, ident, ident).unwrap();
2312                                                 }
2313                                                 is_ref = false;
2314                                                 convert_container!("Vec", 1, || tyref.iter().map(|t| generics.resolve_type(*t)));
2315                                                 unimplemented!("convert_container should return true as container_lookup should succeed for slices");
2316                                         }
2317                                 } else if let syn::Type::Reference(ty) = &*s.elem {
2318                                         let tyref = if from_ownable_ref || !to_c { [&*ty.elem] } else { [&*s.elem] };
2319                                         is_ref = true;
2320                                         convert_container!("Slice", 1, || tyref.iter().map(|t| generics.resolve_type(*t)));
2321                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
2322                                 } else if let syn::Type::Tuple(t) = &*s.elem {
2323                                         // When mapping into a temporary new var, we need to own all the underlying objects.
2324                                         // Thus, we drop any references inside the tuple and convert with non-reference types.
2325                                         let mut elems = syn::punctuated::Punctuated::new();
2326                                         for elem in t.elems.iter() {
2327                                                 if let syn::Type::Reference(r) = elem {
2328                                                         elems.push((*r.elem).clone());
2329                                                 } else {
2330                                                         elems.push(elem.clone());
2331                                                 }
2332                                         }
2333                                         let ty = [syn::Type::Tuple(syn::TypeTuple {
2334                                                 paren_token: t.paren_token, elems
2335                                         })];
2336                                         is_ref = false;
2337                                         ptr_for_ref = true;
2338                                         convert_container!("Slice", 1, || ty.iter());
2339                                         unimplemented!("convert_container should return true as container_lookup should succeed for slices");
2340                                 } else { unimplemented!() }
2341                         },
2342                         syn::Type::Tuple(t) => {
2343                                 if !t.elems.is_empty() {
2344                                         // We don't (yet) support tuple elements which cannot be converted inline
2345                                         write!(w, "let (").unwrap();
2346                                         for idx in 0..t.elems.len() {
2347                                                 if idx != 0 { write!(w, ", ").unwrap(); }
2348                                                 write!(w, "{} orig_{}_{}", if is_ref { "ref" } else { "mut" }, ident, idx).unwrap();
2349                                         }
2350                                         write!(w, ") = {}{}; ", var, if !to_c { ".to_rust()" } else { "" }).unwrap();
2351                                         // Like other template types, tuples are always mapped as their non-ref
2352                                         // versions for types which have different ref mappings. Thus, we convert to
2353                                         // non-ref versions and handle opaque types with inner pointers manually.
2354                                         for (idx, elem) in t.elems.iter().enumerate() {
2355                                                 if let syn::Type::Path(p) = elem {
2356                                                         let v_name = format!("orig_{}_{}", ident, idx);
2357                                                         let tuple_elem_ident = format_ident!("{}", &v_name);
2358                                                         if self.write_conversion_new_var_intern(w, &tuple_elem_ident, &v_name, elem, generics,
2359                                                                         false, ptr_for_ref, to_c, from_ownable_ref,
2360                                                                         path_lookup, container_lookup, var_prefix, var_suffix) {
2361                                                                 write!(w, " ").unwrap();
2362                                                                 // Opaque types with inner pointers shouldn't ever create new stack
2363                                                                 // variables, so we don't handle it and just assert that it doesn't
2364                                                                 // here.
2365                                                                 assert!(!self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics)));
2366                                                         }
2367                                                 }
2368                                         }
2369                                         write!(w, "let mut local_{} = (", ident).unwrap();
2370                                         for (idx, elem) in t.elems.iter().enumerate() {
2371                                                 let real_elem = generics.resolve_type(&elem);
2372                                                 let ty_has_inner = {
2373                                                                 if to_c {
2374                                                                         // "To C ptr_for_ref" means "return the regular object with
2375                                                                         // is_owned set to false", which is totally what we want
2376                                                                         // if we're about to set ty_has_inner.
2377                                                                         ptr_for_ref = true;
2378                                                                 }
2379                                                                 if let syn::Type::Reference(t) = real_elem {
2380                                                                         if let syn::Type::Path(p) = &*t.elem {
2381                                                                                 self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
2382                                                                         } else { false }
2383                                                                 } else if let syn::Type::Path(p) = real_elem {
2384                                                                         self.c_type_has_inner_from_path(&self.resolve_path(&p.path, generics))
2385                                                                 } else { false }
2386                                                         };
2387                                                 if idx != 0 { write!(w, ", ").unwrap(); }
2388                                                 var_prefix(w, real_elem, generics, is_ref && ty_has_inner, ptr_for_ref, false);
2389                                                 if is_ref && ty_has_inner {
2390                                                         // For ty_has_inner, the regular var_prefix mapping will take a
2391                                                         // reference, so deref once here to make sure we keep the original ref.
2392                                                         write!(w, "*").unwrap();
2393                                                 }
2394                                                 write!(w, "orig_{}_{}", ident, idx).unwrap();
2395                                                 if is_ref && !ty_has_inner {
2396                                                         // If we don't have an inner variable's reference to maintain, just
2397                                                         // hope the type is Clonable and use that.
2398                                                         write!(w, ".clone()").unwrap();
2399                                                 }
2400                                                 var_suffix(w, real_elem, generics, is_ref && ty_has_inner, ptr_for_ref, false);
2401                                         }
2402                                         write!(w, "){};", if to_c { ".into()" } else { "" }).unwrap();
2403                                         true
2404                                 } else { false }
2405                         },
2406                         _ => unimplemented!(),
2407                 }
2408         }
2409
2410         pub fn write_to_c_conversion_new_var_inner<W: std::io::Write>(&self, w: &mut W, ident: &syn::Ident, var_access: &str, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool, from_ownable_ref: bool) -> bool {
2411                 self.write_conversion_new_var_intern(w, ident, var_access, t, generics, from_ownable_ref, ptr_for_ref, true, from_ownable_ref,
2412                         &|a, b| self.to_c_conversion_new_var_from_path(a, b),
2413                         &|a, b, c, d, e| self.to_c_conversion_container_new_var(generics, a, b, c, d, e),
2414                         // We force ptr_for_ref here since we can't generate a ref on one line and use it later
2415                         &|a, b, c, d, e, f| self.write_to_c_conversion_inline_prefix_inner(a, b, c, d, e, f),
2416                         &|a, b, c, d, e, f| self.write_to_c_conversion_inline_suffix_inner(a, b, c, d, e, f))
2417         }
2418         pub fn write_to_c_conversion_new_var<W: std::io::Write>(&self, w: &mut W, ident: &syn::Ident, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) -> bool {
2419                 self.write_to_c_conversion_new_var_inner(w, ident, &format!("{}", ident), t, generics, ptr_for_ref, false)
2420         }
2421         /// Prints new-var conversion for an "ownable_ref" type, ie prints conversion for
2422         /// `create_ownable_reference(t)`, not `t` itself.
2423         pub fn write_to_c_conversion_from_ownable_ref_new_var<W: std::io::Write>(&self, w: &mut W, ident: &syn::Ident, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
2424                 self.write_to_c_conversion_new_var_inner(w, ident, &format!("{}", ident), t, generics, true, true)
2425         }
2426         pub fn write_from_c_conversion_new_var<W: std::io::Write>(&self, w: &mut W, ident: &syn::Ident, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
2427                 self.write_conversion_new_var_intern(w, ident, &format!("{}", ident), t, generics, false, false, false, false,
2428                         &|a, b| self.from_c_conversion_new_var_from_path(a, b),
2429                         &|a, b, c, d, e| self.from_c_conversion_container_new_var(generics, a, b, c, d, e),
2430                         // We force ptr_for_ref here since we can't generate a ref on one line and use it later
2431                         &|a, b, c, d, e, _f| self.write_from_c_conversion_prefix_inner(a, b, c, d, e),
2432                         &|a, b, c, d, e, _f| self.write_from_c_conversion_suffix_inner(a, b, c, d, e))
2433         }
2434
2435         // ******************************************************
2436         // *** C Container Type Equivalent and alias Printing ***
2437         // ******************************************************
2438
2439         fn write_template_generics<'b, W: std::io::Write>(&self, w: &mut W, args: &mut dyn Iterator<Item=&'b syn::Type>, generics: Option<&GenericTypes>, is_ref: bool) -> bool {
2440                 for (idx, t) in args.enumerate() {
2441                         if idx != 0 {
2442                                 write!(w, ", ").unwrap();
2443                         }
2444                         if let syn::Type::Reference(r_arg) = t {
2445                                 assert!(!is_ref); // We don't currently support outer reference types for non-primitive inners
2446
2447                                 if !self.write_c_type_intern(w, &*r_arg.elem, generics, false, false, false, true, true) { return false; }
2448
2449                                 // While write_c_type_intern, above is correct, we don't want to blindly convert a
2450                                 // reference to something stupid, so check that the container is either opaque or a
2451                                 // predefined type (currently only Transaction).
2452                                 if let syn::Type::Path(p_arg) = &*r_arg.elem {
2453                                         let resolved = self.resolve_path(&p_arg.path, generics);
2454                                         assert!(self.crate_types.opaques.get(&resolved).is_some() ||
2455                                                         self.c_type_from_path(&resolved, true, true).is_some(), "Template generics should be opaque or have a predefined mapping");
2456                                 } else { unimplemented!(); }
2457                         } else if let syn::Type::Path(p_arg) = t {
2458                                 if let Some(resolved) = self.maybe_resolve_path(&p_arg.path, generics) {
2459                                         if !self.is_primitive(&resolved) {
2460                                                 assert!(!is_ref); // We don't currently support outer reference types for non-primitive inners
2461                                         }
2462                                 } else {
2463                                         assert!(!is_ref); // We don't currently support outer reference types for non-primitive inners
2464                                 }
2465                                 if !self.write_c_type_intern(w, t, generics, false, false, false, true, true) { return false; }
2466                         } else {
2467                                 // We don't currently support outer reference types for non-primitive inners,
2468                                 // except for the empty tuple.
2469                                 if let syn::Type::Tuple(t_arg) = t {
2470                                         assert!(t_arg.elems.len() == 0 || !is_ref);
2471                                 } else {
2472                                         assert!(!is_ref);
2473                                 }
2474                                 if !self.write_c_type_intern(w, t, generics, false, false, false, true, true) { return false; }
2475                         }
2476                 }
2477                 true
2478         }
2479         fn check_create_container(&self, mangled_container: String, container_type: &str, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, is_ref: bool) -> bool {
2480                 if !self.crate_types.templates_defined.borrow().get(&mangled_container).is_some() {
2481                         let mut created_container: Vec<u8> = Vec::new();
2482
2483                         if container_type == "Result" {
2484                                 let mut a_ty: Vec<u8> = Vec::new();
2485                                 if let syn::Type::Tuple(tup) = args.iter().next().unwrap() {
2486                                         if tup.elems.is_empty() {
2487                                                 write!(&mut a_ty, "()").unwrap();
2488                                         } else {
2489                                                 if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t).take(1), generics, is_ref) { return false; }
2490                                         }
2491                                 } else {
2492                                         if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t).take(1), generics, is_ref) { return false; }
2493                                 }
2494
2495                                 let mut b_ty: Vec<u8> = Vec::new();
2496                                 if let syn::Type::Tuple(tup) = args.iter().skip(1).next().unwrap() {
2497                                         if tup.elems.is_empty() {
2498                                                 write!(&mut b_ty, "()").unwrap();
2499                                         } else {
2500                                                 if !self.write_template_generics(&mut b_ty, &mut args.iter().map(|t| *t).skip(1), generics, is_ref) { return false; }
2501                                         }
2502                                 } else {
2503                                         if !self.write_template_generics(&mut b_ty, &mut args.iter().map(|t| *t).skip(1), generics, is_ref) { return false; }
2504                                 }
2505
2506                                 let ok_str = String::from_utf8(a_ty).unwrap();
2507                                 let err_str = String::from_utf8(b_ty).unwrap();
2508                                 let is_clonable = self.is_clonable(&ok_str) && self.is_clonable(&err_str);
2509                                 write_result_block(&mut created_container, &mangled_container, &ok_str, &err_str, is_clonable);
2510                                 if is_clonable {
2511                                         self.crate_types.set_clonable(Self::generated_container_path().to_owned() + "::" + &mangled_container);
2512                                 }
2513                         } else if container_type == "Vec" {
2514                                 let mut a_ty: Vec<u8> = Vec::new();
2515                                 if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t), generics, is_ref) { return false; }
2516                                 let ty = String::from_utf8(a_ty).unwrap();
2517                                 let is_clonable = self.is_clonable(&ty);
2518                                 write_vec_block(&mut created_container, &mangled_container, &ty, is_clonable);
2519                                 if is_clonable {
2520                                         self.crate_types.set_clonable(Self::generated_container_path().to_owned() + "::" + &mangled_container);
2521                                 }
2522                         } else if container_type.ends_with("Tuple") {
2523                                 let mut tuple_args = Vec::new();
2524                                 let mut is_clonable = true;
2525                                 for arg in args.iter() {
2526                                         let mut ty: Vec<u8> = Vec::new();
2527                                         if !self.write_template_generics(&mut ty, &mut [arg].iter().map(|t| **t), generics, is_ref) { return false; }
2528                                         let ty_str = String::from_utf8(ty).unwrap();
2529                                         if !self.is_clonable(&ty_str) {
2530                                                 is_clonable = false;
2531                                         }
2532                                         tuple_args.push(ty_str);
2533                                 }
2534                                 write_tuple_block(&mut created_container, &mangled_container, &tuple_args, is_clonable);
2535                                 if is_clonable {
2536                                         self.crate_types.set_clonable(Self::generated_container_path().to_owned() + "::" + &mangled_container);
2537                                 }
2538                         } else if container_type == "Option" {
2539                                 let mut a_ty: Vec<u8> = Vec::new();
2540                                 if !self.write_template_generics(&mut a_ty, &mut args.iter().map(|t| *t), generics, is_ref) { return false; }
2541                                 let ty = String::from_utf8(a_ty).unwrap();
2542                                 let is_clonable = self.is_clonable(&ty);
2543                                 write_option_block(&mut created_container, &mangled_container, &ty, is_clonable);
2544                                 if is_clonable {
2545                                         self.crate_types.set_clonable(Self::generated_container_path().to_owned() + "::" + &mangled_container);
2546                                 }
2547                         } else {
2548                                 unreachable!();
2549                         }
2550                         self.crate_types.write_new_template(mangled_container.clone(), true, &created_container);
2551                 }
2552                 true
2553         }
2554         fn path_to_generic_args(path: &syn::Path) -> Vec<&syn::Type> {
2555                 if let syn::PathArguments::AngleBracketed(args) = &path.segments.iter().next().unwrap().arguments {
2556                         args.args.iter().map(|gen| if let syn::GenericArgument::Type(t) = gen { t } else { unimplemented!() }).collect()
2557                 } else { unimplemented!(); }
2558         }
2559         fn write_c_mangled_container_path_intern<W: std::io::Write>
2560                         (&self, w: &mut W, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, ident: &str, is_ref: bool, is_mut: bool, ptr_for_ref: bool, in_type: bool) -> bool {
2561                 let mut mangled_type: Vec<u8> = Vec::new();
2562                 if !self.is_transparent_container(ident, is_ref, args.iter().map(|a| *a), generics) {
2563                         write!(w, "C{}_", ident).unwrap();
2564                         write!(mangled_type, "C{}_", ident).unwrap();
2565                 } else { assert_eq!(args.len(), 1); }
2566                 for arg in args.iter() {
2567                         macro_rules! write_path {
2568                                 ($p_arg: expr, $extra_write: expr) => {
2569                                         if let Some(subtype) = self.maybe_resolve_path(&$p_arg.path, generics) {
2570                                                 if self.is_transparent_container(ident, is_ref, args.iter().map(|a| *a), generics) {
2571                                                         if !in_type {
2572                                                                 if self.c_type_has_inner_from_path(&subtype) {
2573                                                                         if !self.write_c_path_intern(w, &$p_arg.path, generics, is_ref, is_mut, ptr_for_ref, false, true) { return false; }
2574                                                                 } else {
2575                                                                         if let Some(arr_ty) = self.is_real_type_array(&subtype) {
2576                                                                                 if !self.write_c_type_intern(w, &arr_ty, generics, false, true, false, false, true) { return false; }
2577                                                                         } else {
2578                                                                                 // Option<T> needs to be converted to a *mut T, ie mut ptr-for-ref
2579                                                                                 if !self.write_c_path_intern(w, &$p_arg.path, generics, true, true, true, false, true) { return false; }
2580                                                                         }
2581                                                                 }
2582                                                         } else {
2583                                                                 write!(w, "{}", $p_arg.path.segments.last().unwrap().ident).unwrap();
2584                                                         }
2585                                                 } else if self.is_known_container(&subtype, is_ref) || self.is_path_transparent_container(&$p_arg.path, generics, is_ref) {
2586                                                         if !self.write_c_mangled_container_path_intern(w, Self::path_to_generic_args(&$p_arg.path), generics,
2587                                                                         &subtype, is_ref, is_mut, ptr_for_ref, true) {
2588                                                                 return false;
2589                                                         }
2590                                                         self.write_c_mangled_container_path_intern(&mut mangled_type, Self::path_to_generic_args(&$p_arg.path),
2591                                                                 generics, &subtype, is_ref, is_mut, ptr_for_ref, true);
2592                                                         if let Some(w2) = $extra_write as Option<&mut Vec<u8>> {
2593                                                                 self.write_c_mangled_container_path_intern(w2, Self::path_to_generic_args(&$p_arg.path),
2594                                                                         generics, &subtype, is_ref, is_mut, ptr_for_ref, true);
2595                                                         }
2596                                                 } else {
2597                                                         let id = subtype.rsplitn(2, ':').next().unwrap(); // Get the "Base" name of the resolved type
2598                                                         write!(w, "{}", id).unwrap();
2599                                                         write!(mangled_type, "{}", id).unwrap();
2600                                                         if let Some(w2) = $extra_write as Option<&mut Vec<u8>> {
2601                                                                 write!(w2, "{}", id).unwrap();
2602                                                         }
2603                                                 }
2604                                         } else { return false; }
2605                                 }
2606                         }
2607                         match generics.resolve_type(arg) {
2608                                 syn::Type::Tuple(tuple) => {
2609                                         if tuple.elems.len() == 0 {
2610                                                 write!(w, "None").unwrap();
2611                                                 write!(mangled_type, "None").unwrap();
2612                                         } else {
2613                                                 let mut mangled_tuple_type: Vec<u8> = Vec::new();
2614
2615                                                 // Figure out what the mangled type should look like. To disambiguate
2616                                                 // ((A, B), C) and (A, B, C) we prefix the generic args with a _ and suffix
2617                                                 // them with a Z. Ideally we wouldn't use Z, but not many special chars are
2618                                                 // available for use in type names.
2619                                                 write!(w, "C{}Tuple_", tuple.elems.len()).unwrap();
2620                                                 write!(mangled_type, "C{}Tuple_", tuple.elems.len()).unwrap();
2621                                                 write!(mangled_tuple_type, "C{}Tuple_", tuple.elems.len()).unwrap();
2622                                                 for elem in tuple.elems.iter() {
2623                                                         if let syn::Type::Path(p) = elem {
2624                                                                 write_path!(p, Some(&mut mangled_tuple_type));
2625                                                         } else if let syn::Type::Reference(refelem) = elem {
2626                                                                 if let syn::Type::Path(p) = &*refelem.elem {
2627                                                                         write_path!(p, Some(&mut mangled_tuple_type));
2628                                                                 } else { return false; }
2629                                                         } else { return false; }
2630                                                 }
2631                                                 write!(w, "Z").unwrap();
2632                                                 write!(mangled_type, "Z").unwrap();
2633                                                 write!(mangled_tuple_type, "Z").unwrap();
2634                                                 if !self.check_create_container(String::from_utf8(mangled_tuple_type).unwrap(),
2635                                                                 &format!("{}Tuple", tuple.elems.len()), tuple.elems.iter().collect(), generics, is_ref) {
2636                                                         return false;
2637                                                 }
2638                                         }
2639                                 },
2640                                 syn::Type::Path(p_arg) => {
2641                                         write_path!(p_arg, None);
2642                                 },
2643                                 syn::Type::Reference(refty) => {
2644                                         if let syn::Type::Path(p_arg) = &*refty.elem {
2645                                                 write_path!(p_arg, None);
2646                                         } else if let syn::Type::Slice(_) = &*refty.elem {
2647                                                 // write_c_type will actually do exactly what we want here, we just need to
2648                                                 // make it a pointer so that its an option. Note that we cannot always convert
2649                                                 // the Vec-as-slice (ie non-ref types) containers, so sometimes need to be able
2650                                                 // to edit it, hence we use *mut here instead of *const.
2651                                                 if args.len() != 1 { return false; }
2652                                                 write!(w, "*mut ").unwrap();
2653                                                 self.write_c_type(w, arg, None, true);
2654                                         } else { return false; }
2655                                 },
2656                                 syn::Type::Array(a) => {
2657                                         if let syn::Type::Path(p_arg) = &*a.elem {
2658                                                 let resolved = self.resolve_path(&p_arg.path, generics);
2659                                                 if !self.is_primitive(&resolved) { return false; }
2660                                                 if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(len), .. }) = &a.len {
2661                                                         if self.c_type_from_path(&format!("[{}; {}]", resolved, len.base10_digits()), is_ref, ptr_for_ref).is_none() { return false; }
2662                                                         if in_type || args.len() != 1 {
2663                                                                 write!(w, "_{}{}", resolved, len.base10_digits()).unwrap();
2664                                                                 write!(mangled_type, "_{}{}", resolved, len.base10_digits()).unwrap();
2665                                                         } else {
2666                                                                 let arrty = format!("[{}; {}]", resolved, len.base10_digits());
2667                                                                 let realty = self.c_type_from_path(&arrty, is_ref, ptr_for_ref).unwrap_or(&arrty);
2668                                                                 write!(w, "{}", realty).unwrap();
2669                                                                 write!(mangled_type, "{}", realty).unwrap();
2670                                                         }
2671                                                 } else { return false; }
2672                                         } else { return false; }
2673                                 },
2674                                 _ => { return false; },
2675                         }
2676                 }
2677                 if self.is_transparent_container(ident, is_ref, args.iter().map(|a| *a), generics) { return true; }
2678                 // Push the "end of type" Z
2679                 write!(w, "Z").unwrap();
2680                 write!(mangled_type, "Z").unwrap();
2681
2682                 // Make sure the type is actually defined:
2683                 self.check_create_container(String::from_utf8(mangled_type).unwrap(), ident, args, generics, is_ref)
2684         }
2685         fn write_c_mangled_container_path<W: std::io::Write>(&self, w: &mut W, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, ident: &str, is_ref: bool, is_mut: bool, ptr_for_ref: bool) -> bool {
2686                 if !self.is_transparent_container(ident, is_ref, args.iter().map(|a| *a), generics) {
2687                         write!(w, "{}::", Self::generated_container_path()).unwrap();
2688                 }
2689                 self.write_c_mangled_container_path_intern(w, args, generics, ident, is_ref, is_mut, ptr_for_ref, false)
2690         }
2691         pub fn get_c_mangled_container_type(&self, args: Vec<&syn::Type>, generics: Option<&GenericTypes>, template_name: &str) -> Option<String> {
2692                 let mut out = Vec::new();
2693                 if !self.write_c_mangled_container_path(&mut out, args, generics, template_name, false, false, false) {
2694                         return None;
2695                 }
2696                 Some(String::from_utf8(out).unwrap())
2697         }
2698
2699         // **********************************
2700         // *** C Type Equivalent Printing ***
2701         // **********************************
2702
2703         fn write_c_path_intern<W: std::io::Write>(&self, w: &mut W, path: &syn::Path, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool, with_ref_lifetime: bool, c_ty: bool) -> bool {
2704                 let full_path = match self.maybe_resolve_path(&path, generics) {
2705                         Some(path) => path, None => return false };
2706                 if let Some(c_type) = self.c_type_from_path(&full_path, is_ref, ptr_for_ref) {
2707                         write!(w, "{}", c_type).unwrap();
2708                         true
2709                 } else if self.crate_types.traits.get(&full_path).is_some() {
2710                         // Note that we always use the crate:: prefix here as we are always referring to a
2711                         // concrete object which is of the generated type, it just implements the upstream
2712                         // type.
2713                         if is_ref && ptr_for_ref {
2714                                 write!(w, "*{} crate::{}", if is_mut { "mut" } else { "const" }, full_path).unwrap();
2715                         } else if is_ref {
2716                                 if with_ref_lifetime { unimplemented!(); }
2717                                 write!(w, "&{}crate::{}", if is_mut { "mut " } else { "" }, full_path).unwrap();
2718                         } else {
2719                                 write!(w, "crate::{}", full_path).unwrap();
2720                         }
2721                         true
2722                 } else if self.crate_types.opaques.get(&full_path).is_some() || self.crate_types.mirrored_enums.get(&full_path).is_some() {
2723                         let crate_pfx = if c_ty { "crate::" } else { "" };
2724                         if is_ref && ptr_for_ref {
2725                                 // ptr_for_ref implies we're returning the object, which we can't really do for
2726                                 // opaque or mirrored types without box'ing them, which is quite a waste, so return
2727                                 // the actual object itself (for opaque types we'll set the pointer to the actual
2728                                 // type and note that its a reference).
2729                                 write!(w, "{}{}", crate_pfx, full_path).unwrap();
2730                         } else if is_ref && with_ref_lifetime {
2731                                 assert!(!is_mut);
2732                                 // If we're concretizing something with a lifetime parameter, we have to pick a
2733                                 // lifetime, of which the only real available choice is `static`, obviously.
2734                                 write!(w, "&'static {}", crate_pfx).unwrap();
2735                                 if !c_ty {
2736                                         self.write_rust_path(w, generics, path);
2737                                 } else {
2738                                         // We shouldn't be mapping references in types, so panic here
2739                                         unimplemented!();
2740                                 }
2741                         } else if is_ref {
2742                                 write!(w, "&{}{}{}", if is_mut { "mut " } else { "" }, crate_pfx, full_path).unwrap();
2743                         } else {
2744                                 write!(w, "{}{}", crate_pfx, full_path).unwrap();
2745                         }
2746                         true
2747                 } else {
2748                         false
2749                 }
2750         }
2751         fn write_c_type_intern<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, is_ref: bool, is_mut: bool, ptr_for_ref: bool, with_ref_lifetime: bool, c_ty: bool) -> bool {
2752                 match generics.resolve_type(t) {
2753                         syn::Type::Path(p) => {
2754                                 if p.qself.is_some() {
2755                                         return false;
2756                                 }
2757                                 if let Some(full_path) = self.maybe_resolve_path(&p.path, generics) {
2758                                         if self.is_known_container(&full_path, is_ref) || self.is_path_transparent_container(&p.path, generics, is_ref) {
2759                                                 return self.write_c_mangled_container_path(w, Self::path_to_generic_args(&p.path), generics, &full_path, is_ref, is_mut, ptr_for_ref);
2760                                         }
2761                                         if let Some(aliased_type) = self.crate_types.type_aliases.get(&full_path).cloned() {
2762                                                 return self.write_c_type_intern(w, &aliased_type, None, is_ref, is_mut, ptr_for_ref, with_ref_lifetime, c_ty);
2763                                         }
2764                                 }
2765                                 self.write_c_path_intern(w, &p.path, generics, is_ref, is_mut, ptr_for_ref, with_ref_lifetime, c_ty)
2766                         },
2767                         syn::Type::Reference(r) => {
2768                                 self.write_c_type_intern(w, &*r.elem, generics, true, r.mutability.is_some(), ptr_for_ref, with_ref_lifetime, c_ty)
2769                         },
2770                         syn::Type::Array(a) => {
2771                                 if is_ref && is_mut {
2772                                         write!(w, "*mut [").unwrap();
2773                                         if !self.write_c_type_intern(w, &a.elem, generics, false, false, ptr_for_ref, with_ref_lifetime, c_ty) { return false; }
2774                                 } else if is_ref {
2775                                         write!(w, "*const [").unwrap();
2776                                         if !self.write_c_type_intern(w, &a.elem, generics, false, false, ptr_for_ref, with_ref_lifetime, c_ty) { return false; }
2777                                 } else {
2778                                         let mut typecheck = Vec::new();
2779                                         if !self.write_c_type_intern(&mut typecheck, &a.elem, generics, false, false, ptr_for_ref, with_ref_lifetime, c_ty) { return false; }
2780                                         if typecheck[..] != ['u' as u8, '8' as u8] { return false; }
2781                                 }
2782                                 if let syn::Expr::Lit(l) = &a.len {
2783                                         if let syn::Lit::Int(i) = &l.lit {
2784                                                 if !is_ref {
2785                                                         if let Some(ty) = self.c_type_from_path(&format!("[u8; {}]", i.base10_digits()), false, ptr_for_ref) {
2786                                                                 write!(w, "{}", ty).unwrap();
2787                                                                 true
2788                                                         } else { false }
2789                                                 } else {
2790                                                         write!(w, "; {}]", i).unwrap();
2791                                                         true
2792                                                 }
2793                                         } else { false }
2794                                 } else { false }
2795                         }
2796                         syn::Type::Slice(s) => {
2797                                 if !is_ref || is_mut { return false; }
2798                                 if let syn::Type::Path(p) = &*s.elem {
2799                                         let resolved = self.resolve_path(&p.path, generics);
2800                                         if self.is_primitive(&resolved) {
2801                                                 write!(w, "{}::{}slice", Self::container_templ_path(), resolved).unwrap();
2802                                                 true
2803                                         } else {
2804                                                 let mut inner_c_ty = Vec::new();
2805                                                 assert!(self.write_c_path_intern(&mut inner_c_ty, &p.path, generics, true, false, ptr_for_ref, with_ref_lifetime, c_ty));
2806                                                 if self.is_clonable(&String::from_utf8(inner_c_ty).unwrap()) {
2807                                                         if let Some(id) = p.path.get_ident() {
2808                                                                 let mangled_container = format!("CVec_{}Z", id);
2809                                                                 write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
2810                                                                 self.check_create_container(mangled_container, "Vec", vec![&*s.elem], generics, false)
2811                                                         } else { false }
2812                                                 } else { false }
2813                                         }
2814                                 } else if let syn::Type::Reference(r) = &*s.elem {
2815                                         if let syn::Type::Path(p) = &*r.elem {
2816                                                 // Slices with "real types" inside are mapped as the equivalent non-ref Vec
2817                                                 let resolved = self.resolve_path(&p.path, generics);
2818                                                 let mangled_container = if let Some((ident, _)) = self.crate_types.opaques.get(&resolved) {
2819                                                         format!("CVec_{}Z", ident)
2820                                                 } else if let Some(en) = self.crate_types.mirrored_enums.get(&resolved) {
2821                                                         format!("CVec_{}Z", en.ident)
2822                                                 } else if let Some(id) = p.path.get_ident() {
2823                                                         format!("CVec_{}Z", id)
2824                                                 } else { return false; };
2825                                                 write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
2826                                                 self.check_create_container(mangled_container, "Vec", vec![&*r.elem], generics, false)
2827                                         } else if let syn::Type::Slice(sl2) = &*r.elem {
2828                                                 if let syn::Type::Reference(r2) = &*sl2.elem {
2829                                                         if let syn::Type::Path(p) = &*r2.elem {
2830                                                                 // Slices with slices with opaque types (with is_owned flags) are mapped as non-ref Vecs
2831                                                                 let resolved = self.resolve_path(&p.path, generics);
2832                                                                 let mangled_container = if let Some((ident, _)) = self.crate_types.opaques.get(&resolved) {
2833                                                                         format!("CVec_CVec_{}ZZ", ident)
2834                                                                 } else { return false; };
2835                                                                 write!(w, "{}::{}", Self::generated_container_path(), mangled_container).unwrap();
2836                                                                 let inner = &r2.elem;
2837                                                                 let vec_ty: syn::Type = syn::parse_quote!(Vec<#inner>);
2838                                                                 self.check_create_container(mangled_container, "Vec", vec![&vec_ty], generics, false)
2839                                                         } else { false }
2840                                                 } else { false }
2841                                         } else { false }
2842                                 } else if let syn::Type::Tuple(_) = &*s.elem {
2843                                         let mut args = syn::punctuated::Punctuated::<_, syn::token::Comma>::new();
2844                                         args.push(syn::GenericArgument::Type((*s.elem).clone()));
2845                                         let mut segments = syn::punctuated::Punctuated::new();
2846                                         segments.push(parse_quote!(Vec<#args>));
2847                                         self.write_c_type_intern(w, &syn::Type::Path(syn::TypePath { qself: None, path: syn::Path { leading_colon: None, segments } }), generics, false, is_mut, ptr_for_ref, with_ref_lifetime, c_ty)
2848                                 } else { false }
2849                         },
2850                         syn::Type::Tuple(t) => {
2851                                 if t.elems.len() == 0 {
2852                                         true
2853                                 } else {
2854                                         self.write_c_mangled_container_path(w, t.elems.iter().collect(), generics,
2855                                                 &format!("{}Tuple", t.elems.len()), is_ref, is_mut, ptr_for_ref)
2856                                 }
2857                         },
2858                         _ => false,
2859                 }
2860         }
2861         pub fn write_c_type<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) {
2862                 assert!(self.write_c_type_intern(w, t, generics, false, false, ptr_for_ref, false, true));
2863         }
2864         pub fn write_c_type_in_generic_param<W: std::io::Write>(&self, w: &mut W, t: &syn::Type, generics: Option<&GenericTypes>, ptr_for_ref: bool) {
2865                 assert!(self.write_c_type_intern(w, t, generics, false, false, ptr_for_ref, true, false));
2866         }
2867         pub fn understood_c_path(&self, p: &syn::Path) -> bool {
2868                 self.write_c_path_intern(&mut std::io::sink(), p, None, false, false, false, false, true)
2869         }
2870         pub fn understood_c_type(&self, t: &syn::Type, generics: Option<&GenericTypes>) -> bool {
2871                 self.write_c_type_intern(&mut std::io::sink(), t, generics, false, false, false, false, true)
2872         }
2873 }